Let’s master PERCENT…..Step-by-Step…..
Vložit
- čas přidán 26. 10. 2021
- TabletClass Math:
tcmathacademy.com/
Math help with percent. For more math help to include math lessons, practice problems and math tutorials check out my full math help program at tcmathacademy.com/
Math Notes:
Pre-Algebra Notes: tabletclass-math.creator-spri...
Algebra Notes: tabletclass-math.creator-spri...
Geometry Notes: tabletclass-math.creator-spri...
Algebra 2 / Trig Notes: tabletclass-math.creator-spri...
When I was a kid I couldn't understand any math at all. When I grew up and went to college the teachers explained this just like you do. I do Algebra in my head now. It is my own personal Crossword Puzzle Type of entertainment. When I am stressed or bored I do algebra problems. Thank you for your Lucid explanations of these difficult concepts.
For some people, their brains just need a little more time to mature ( for lack of a better word, but I mean -biologically mature) before they can grasp things well in mathematics. Sometimes they will be struggling with math, like in grades up to even 11 or 12, then suddenly a year later, something just clicks and they can do it. Having a good teacher is very helpful, of course.
Oh I did an access course a route to degree level education here in the UK. I couldn't do stuff like this. I asked the what will I use it for. He never answered my question directly, he just changed the the terms, so it fitted with what I was learning! Brilliant.
Wow, what teachers were those. Not any math teacher I ever had!!! You are so blessed.
@@paddlefar9175 For some people, they just had poorly conceived and poorly written textbooks, often with woefully less than adequate guidance in math classes.
The definitive textbooks for ALGEBRA are the Algebra Programmed textsbooks by Robert D. Hackworth and Robert H. Alwin.
Other texts are indeed quite inferior.
One needs no teacher other than those texts.
@@thomassicard3733 Thanks for the information.
There is a much simpler solution.
Divide 3 by 18% = 0.1666
Multiply 0.1666 by 100% = 16.6666
Works every time.
Good
Multiply it by 100, not "100%"
Um 3/.18: 16.667. How much simpler than that can it get. No need to multiply anything. 3 divided by .18 = 16.667...
Yes, but for people who don't know percentages or who are not familiar with them, how did you know to divide 3 by 18%? And how can you teach this in a way that someone who is not familiar can learn what numbers to divide on their own? Of course, once you know it, it's very easy, but the hard part is to present it in a way to make it easy for those still learning.
Basic arithmetic. Not really "math" Could do this when I was a kid.
Percent comes from Latin meaning "Per Centum" which translates as "For every 100". The symbol % is a stylized fraction representing 1/100 which means one hundredth which is 0.01. Therefore 18% means 18 hundredths which is 18/100 = 0.18. Therefore the answer to the question 18% of what number equals 3 can be simply solved by calculating 3 ÷ 0.18 = 16.666...
Wow I wish I could do that thank you for sharing
Use this ratio 3/n = 18/100 then cross multiply 3*100 = 18n then n= 300/18 and n = 16.667. Simple algebra seems to work best for me because I can use 'n' to find not only percent but any of the numbers in the ratio 3, 16.667, 18, or 100. The ratio must answer the question. Example: 3 is what percent of 16.667 would be 3/16.667 = n/100 now cross multiply
I'm sure glad I learned math in the early 60's. Your approach is cumbersome, not only here but in all the various math problems you explain, and can be explained much easier in other ways.
I agree, but The new method is so much easier than in 60's. Don't feel bad getting the wrong answer. Don't have your self esteem destroyed by the teacher correcting your answer. You cannot go through life knowing you are a math failure. Write down any answer you "feel" like. In modern school Mr. Bob, you would be expelled for hurting TabletClass Math instructor's self esteem. I am being sarcastic. Don't get all excited and good day to you.
@@garybray3614 so much “easier”? Lol That’s a joke, right?
Maybe for you but not for everyone
@ Bob, Washington State ~ Then why are you here?
I'm thinkin' maybe 'overly thorough' but a good foundation for solid reasoning later.
I learned that the 'of' in math means multiplication, and you can undo multiplication with division and vice versa. And turning a percent into a decimal moves it two places to the left. Therefore, 18% (x) =3 is 3 ÷ .18 = ~17.
Simple. 3 divided by 18 (or 1 divided by 6, if you´re doing it in your head) times by 100 equals 16.6666666666. I´ve found that by keeping budgets ever since I´ve left school while avoiding calculators, I have kept my sense of maths from my schooldays. Also, by having a set of counting bricks as a small kid helped a lot.
Nice job. A stellar review! Thanks, keep up the good work!
'What makes John so Boss is that he creates stealth difficult equations. John always needs to apply hairspray
to his math problems. Then, when you think you can't solve the problem, he applies a solution based conditioner. John, you
are truly a wonderful presence on you tube. I'm a fan and I have never had math instruction on such a top tier level. Thank you so much.
MR. TabletClass Math, thank you for a fantastic lecture on Percent's in Mathematics.
At 71 you've finally made this understandable and fun!
I love learning math again at 65 years of age. If I may offer with respect, because you are a good teacher. Perhaps less chitchat? I scrolled down while you were talking and learned how to solve the problem two minutes in. Now I can learn to solve other problems or practice what I've learned with the other 18 minutes. Thank you for your efforts.
Thanks 🙏 keep fully explaining every step 👍
I learned it as 3 ÷ 0.18 since percent is short for per centum and centum is 100.
Same here kind of. I learned it as 3 / 18 then hit the % key then the = key
@@kimlancaster7 n
Me too.
@@kimlancaster7 pop smoke
When I think about percent, I realize it is another way to multiply, therefore the commutative property applies. Something most people don't realize is that a%(b) always equals b%(a). Especially if you're doing the percentage in your head, you might find that swapping the two terms helps. For example: 18% of 25 is hard to do in your head, but 25% of 18 is easy -- It's just half of half. 4.5. All good wishes.
One thing I think I"m fair at. Make a fraction, 100 over 18 = X over 3. Cross multiply to solve, Multiply 3 x 100, then divide by 18. - 16.6667. I honestly think making proportions is my most used math in the business world. The widget company says we sold 18% of their widgits. We sold 300 units. We know that the widgit company sold 1667 total units into the market.
I used to think going to the fraction was the best way but watching him made me realize his way of decimals is SUPERIOR!
It helps if you've internalized some of the fractional conversions like 25%= .25 to help cross check your results.
In the alphabet, d comes before p. You read left to right, so move the decimal to the right to go from decimal to percent. And vice versa for percent to decimal.
Super helpful -- thank you!
Blessed Happy New Year To You And Family Wonderful Teacher
Thanks for the refresher!💞
Percents are not complicated. If you see a percent sign, move the decimal two places to the left. Period. And simplify as follows;
0.18x =3
X=3/0.18
X =16.6667
Done
Do not move decimal point blindly. Use logic. When you multiply by 10, 100, 1000 The number becomes ten fold, hundred fold and so on.
When same if you devide, It becomes tenth, hundredth , so you move the point accordingly right or left.
Learned that in 8th grade algebra, 1972. Back then, all kids taught this method, now we need videos to explain it? Dependence = loss of power
@@hradaykantsaraiya7779 , I don’t recall using the word “blindly” or “any-which-way”. You are characterizing me as an illiterate imbecile. Not appreciated.
@@barneyrubble4827 Sadly, there are still many adults in this day and age who don't understand percentages. Though many may have been taught it in school, not everyone actually learned it or remembers it. Videos are a good way to help those people catch on in a private and fun way.
It is a good habit before you start a calculation to estimate roughly an answer. 18 % is a little less than 20 %, which is 1/5. So the unknown number should be a little more than 5 times 3, which is 15. So perhaps 16 or 17 would be the expected answer.
Excellent instructional teaching! I'm a college grad whose major was Biochemistry and Botany; needless to say that I had a lot of advanced algebra etc., however I missed this answer by overusing percent calcs. I'm out of practice, but I'm also 66 yrs old.
Nice refresher. Thank you
An old concept taught in general math was parts of 100 and 100/6 is 16 2/3. Methods used before portable calculators were available. This enabled a student to multiply or divide by parts of 100 easily. In this problem for example 300/18 = 100/6 = 16 2/3 .
thank you i knew how to do these problems but you helped shape my understanding
Amazing! Thank you!
Thank you so much! first I was like aw! too much talking lol but then I realized that you are the best:))!!🤗
Thank you for showing it in algebraic form!
He makes it more complicated than it is
Thank you!
I learned to solve these math problems 5 decades ago as ratio problems and still carry them with me today.
IS over OF is equal to PERCENT over 100
or another way to look at it is:
PART over WHOLE is equal to PERCENT over 100 OR PART / WHOLE = % / 100
IS over OF is equal to PERCENT over 100 OR IS / OF = % / 100
Given 1st problem of 18% OF what number (n) IS 3 would be written as:
3 / n = 18 / 100; cross multiply to eliminate denominator: (3)(100) = (18)(n)
Divide by 18 to isolate n ==> 300/18, reduces to 50/3; therefore n = 16.67
Just voted! I have been studying your percent video above--very helpful. Very easy to follow and understand!
Sorry for asking this but... which program are you using as a blackboard?. It's really nice, man!. Thanks in advance, and for your excellent videos.
Good stuff professor !
Oftentimes math problems are good for teaching technique but have no practical use. This problem I see in variations often. Good lesson, Mr. John
18% * x = 3 then (18/100) * x = 3 then 18x/100 = 3 then 18x = 3*100 then x = 300/18 then x = 16,66 (verification: 18% of 16,66 = 2,99 = 3). Answer is 16,66.
I'm 73 years old and still love math. Everybody should have a fab teacher like this gent!
It would be nice if you get to the point in the explantions a lot quicker. So once you give example-as introduction, answer it,then we can see if we are wrong or right. Then build from there.
Good job!
Write, is/of=%/100, fill in the numbers and cross multiply. Easy and works every time.
When I was in grade school I usually received a B+ or A in math, but in 3rd grade I had a little trouble with greater than and less than problems (> and
I'm finding that not fully understanding basics (like at the very beginning) math is showing up as wobbly results now. Like your >/
60mile and hour =96 kmh /80miles an hour =128 using formula 1.6 which = to a mile 🤔
“Of” means multiple. 0.18xA=3! A=3/0.18
I watched this video cause it was bringing back some not so fond memories from when I was a kid. 😂
I read a few comments and I noticed different people have different methods for solving this, which they find very obvious. It's obvious if you understand the "mechanics" and that's exactly what someone needs in order to be able to solve various problems, not just a particular one.
In the past, in some parts of Europe, they were teaching "the rule of 3" very early because it can be used in a lot of situations. Here for example, you can set it up like this: we are looking for some number (x) which we know is the whole (aka 100%). So, if
x is 100(%) and
3 is 18(%)
In the "rule of 3" you multiply diagonally the two known numbers (3 * 100) and then you divide the result by the 3rd known number in order to find x.
Once you understand this technique, you can use it anywhere else, like "3 is what % of 8?" So we know 8 is the 100%:
8-----100(%) then
3----- x(%)?
On one diagonal, you got two known numbers - 3 and 100. Multiply them, then divide by the 3rd remaining known number. The result is the x you were looking for.
Another one he's showing: 32% of 400 - so:
400 is 100%
X is 32%
--------------
Answer: 32*400/100= 128
No need to move decimal points with this method.
Jot it down on a piece of paper the way I did at the beginning, until it becomes second nature and you can just visualize it in your head.
18% of x = 3
6% of x = 1
6% is 100/6
100/6 = 16 2/3 (just using rule-of-thumb percentage table and intuition from practice) *Intuition:*
Intuition can come from simple sanity checks:
18% is near 20%
20 * 5 = 100 ...dealing with percent, `100` is a nice number to shoot for
3 * 5 = 15 ...the number is going to be a little more than 15
With that in mind when 100/6 appeared it seemed reasonable
Greetings. The answer is 16.67 rounded. We determine this value by assuming that the value of the number we wish to find is X and solve for X. Now 18% of X =3, from this we find that 18X=300, thereafter we divide both sides by 18 to get X=16.666 recurring 6. We round to two places to get 16.67.
I did in my head first:
If 3 = 18%, then 1 = 6% , so 10 = 60%.
I need to figure the remaining 40%:
2/3 of 10 = 6.666 equal 40%.
Answer = 10 + 6.666 = 16.666
I then checked with a calculator
3/.18 = 16.666
Got ya I guess I better subscribe I have a seven grader!!
Wow I'm retired at 66 years old did 18% of 3 in my head. That was fun.
I like your refreshing and complex instructions.
(18/100)•x = 3 ;
(100/18)•(18/100)•x = (100/18)•3
Avoiding the decimal okay? No calc.
Well, we have three important information to find the one missing.
The best way we can do this:
18% -> 3
100% -> X
So: X= (100 X 3 ) : 18
X= 300 : 18
X= 16.66
Very easy, logic and fast.
It's a "cross rule": x=(3x100%)/18%. I learned it in chemistry calculating solutions.
This is clearly done. I thank you kindly
Let X be the unknown number
18/100×X=3
X=3×100/18=16.67
No more explanation is required.
@@igoranisimov6549 Thanks!
Commutative property applies as per Anton's post and that often makes percentage calculations easier, but not always....
Any time you see the word "of" it means multiply
What did I learn at school fifty years ago that made it possible for me to figure this out in my head in 20 seconds?
Thank you.
I like to try to figure these out in my head or at least with a minimum amount of calculations, hopefully no calculator. So 18% of a number is three. If you divide the 18 by 3 and divide the 3 by 3, you get 6% (of some number) = 1. 6% = 6/100 times (some number, say x) = 1. Then x = 100/6 = 50/3 = 16.67. You would still have to do the 50/3 calculation, but I think that's pretty easy and fast to do by hand. Anyone else see this problem that way?
No calculator needed for the "18% of what # is 3?". No converting percent to decimal needed. In your head you can figure it to a whole number with fractional remainder.
The only truly correct (as it is exact) answer is 16 2/3 (or 16.6 repeating). 16.67 is approximate and certainly good enough for counting pennies.
Excellent video. To get a number sense, we can look at this problem as first "20% of what is 3?".... 20% is just 1/5th of something, so multiplying 3 by 5 = 15 which gives you the whole. So we know the answer is going to be at least 15 because 18% is less than 20%.
x•0.18 = 3
3÷0.18 = x
3•100/18
300\18
16.6....
Method 1: Using long division 18 goes into 30 1 time. 30 -18 = 12, bring down the zero is 120, 18 goes into 120 6 times, 120 -108 = 12. We have a remander of 12 again which means the number 6 is going to repeat forever.
Method 2: memorize 100÷x where x is 1 to 20. 100÷6 equals 16.6..... this is known from rote.
Interestingly we can find patterns of what next numbers are using multiples. For example 100÷7 = 14.28571 and 100÷14 = 7.14285717... 14 is double 7 and 7.12... is half 14.28.
100÷1 = 100
100÷2 = 50
100÷3 = 33.3... or 33+1/3
100÷4 = 25
100÷5 = 20
100÷6 = 16.6... or 16+2/3
Note that 6 is double 3 and 16.66666... is half of 33.33333... . These are patterns I memorize to predict numbers and solve these types of problems.
100÷7 = 14+2/7
100÷14 = 7+1/7
Note that 7 is half of 14 and 14+2/7 is double 7+1/7.
There is a scaling effect where you have two factors that you multiply the first factor by s and then divide the second factor by s, you have different factors but the same product.
I should stop here but am going to do a few more:
100÷8 = 12.5 note that 1/8 is 0.125.
100÷9 = 11.1... or 11+1/9. Not that ninths are just the numerator repeating like 1/9 = 0.999... 2/9 = 0.222... 8/9 = 0.888... 9/9 = 0.9999... which is exactly 1. This is like thirds because nine is a multiple of 3 so 1/3, 2/3 3/3 is 0.3... 0.6... 0.9... 1/9 is 1/3 divided by 3 so 0.3333... ÷3 = 0.1111.
100÷10 = 10 easy
100÷11 = 0.0909... Note that elevenths are repeating multiples of 9 such as .0909, .1818, .2727, ... .8181. You have 5/9 then it is 0.4545... because 9×5 = 45.
100÷ 12 = 8.3333... or 8 +1/3. We can guess this number after noticing patterns. We often have an oddball number that when dividing 1 or 100 gives thirds or quarters, or multiples of them. This is interesting:
100÷6 = 16.6... 6 is half of 12
100÷12 = 8.3... 8.3.. is half of 16.6...
100÷13 = 7.692307... the numbers repeat, this and divinding by 17 are oddballs because they are prime.
100÷14 = use the information we know about 100÷7
100÷ 15= use the information we know about 100÷5
100÷16 = compare 100÷8
100÷17 = some very strange oddball
100÷18 = half whatever 100÷9 is so 5.5.....
100÷ 19= another prime oddball.
100÷20 = 5
There are patterns, some of it is memorization some of it computing based on what we already know.
If you want to do this one without using a calculator:
(18/100)X = 3 -> Dividing both sides by 3 gives: (6/100)X = 1 -> X = 100/6. Then do the long division on paper and 16,67 is your answer. Right?
Not the general way of doing it, but a way to do it quickly in your head:
18% * x = 3
you can move % around:
x% * 18 = 3
at that point, for some people, it becomes obvious how to do it in one's head.
x% = 1/6, x = 100/6 = 50/3 ~= 16.7
YMMV. I certainly wouldn't bother doing it this way if the question involved numbers that aren't easily manipulated in one's head, e.g., "18.6% of what number is 3.23?"
I saw this as a ratio. 3 is to 18 is the same as X is to 100. 3/18 = X/100. Cross multiply and divide or 3 X 100 / 18 which means that X is equal to 16.66.
You are making it more difficult than it is. Explain it simpler.
Genius might be the ability to say a profound thing in a simple way.
Charles Bukowski
T. O. I think he explains it in depth like he does so that you won't have questions about how this problem is actually solved in the long run. Some people just need to know all the steps to figuring out equations such as this one. Some teachers even require you to know all of the "steps" you need to take to figure out the answers. I'm not trying to be "smart" but I'm just saying that everything in life cannot be simple. 😉
They call that hyperbole
He teaches PRINCIPLES AND PROCEDURES that can be applied to other similar math problems not ANSWERS to just ONE problem!
@@lamper2 I would find it much more useful if he'd list 3 or 4 similar problems and solve them without so much extra talk. The "pattern" of similar solutions will make the lesson much easier ... and more memorable. The extra talk is irritating.
Divide 3 by 18, that will give you 1%. Then multiply the 1% number by 100 and you have your answer
(100 × 3) ÷ 18= 16,6666..
@chreynest - That's exactly how I'd solve it.
However I would explain it like this:
Question
18% of what number (x) is 3?
Solution:
Find 1% of the full amount. I.e. (x).
To do that, take the 3 (which represents 18%) and divide it by the percentage it represents. In this case 18.
This results in 0.16667 and tells us that this is 1% of the full amount (x).
So to find out the full amount (x) (or to put in another way; 100%), you just multiply 0.16667 by 100.
And you'll have your answer.
It's a somewhat more long-winded explanation, but it gives the reason behind the method. Which I think is important.
John, I can’t ever remember being taught or learning about PEMDAS and now I have it helps me no end (I’m 69) I just haven’t nailed the division before multiplication as in the denominator in this operation, can you direct me to a lesson you have done prior so I can investigate please
Why overly complicate it
Just divide 3 by 18 and multiply by 100.
right to the point -> 15:33
I read that as “parent review”. I thought “ITS ABOUT TIME!”🤣💕🤣💕🤣💕
🤣🤣
Percent is the ph of characteristics or atom ratio per measuring system in this case centigrade
Review is the mixing of atom
Awsome teacher
He is awful.
Wunderbar!
I did it in my head. 3 also is 1% of 300. Therefore 18% is one 18th of 300. 300÷18=16.666666...
I doubt whether I could do it in my head if the numbers had a decimal or more.
16 2/3 so50×18/300=3 so 50/3 is the number and that is the answer
Let me put this into a simple equation to save y'all time:
0.18X=3
Meaning that X=3/0.18
X=16.666
x=16.666 so if the third number is 5 or more it goes up one so the answer is 16.67
@@enriqueiii9209 you mean if instead of 3 it was 5?
@@fl0w822 No, you were right the first time, you wrote the answer 16.666 but it should be 16.67. multiply .18 x 16.666 then
.18 x16.67, the answer should be 3 or more not less than 3. I hope you understood what I said.
@@enriqueiii9209 oh gotcha, technically it is 16 and 2 thirds, but for the sake of simplifying the answer I wrote it as .666, rounded up it's actually .667 tho
@@fl0w822 Yes but if .666 your answer is .67
Maybe I’m lazy, but for this problem I just divide 3 by 18. This gives me 1% of the unknown number. Then I multiply by 100 which gives me the answer. I didn’t pay a lot of attention in math classes in school. So I just sort of work out my own system on a lot of math.
THANK YOU!
I thought I was the only one who did it this way.
The trick is to grap that multitply by x = divide by 1/x, and that divide by y = multiply by 1/y. Once this becomes normal thinking then this entire topic is a no-brainer.
I immediately saw this after reading the question: 3 * 100/18 = one sixth of a hundred = 16 2/3
is this correct? please explain: 1⁰ = 1, 5⁰ = 1, 100⁰ = 1
I always approached % by finding 1% then figuring it out from there, Eg from above would be 32 X 4 (1%) = 128 and no calculator needed. Turning it into a decimal is a new way for me to look at this type of problem. x
3x100/18 = 50/3
could use cross multiplication to solve the problem i.e, 18x = 300, x = 16 .6666
The method I use to find out what 18% of what number is equal to 3 is to divide 100% by 18. Ie 100/18 = 5.55 Then 5.55 x 3 = 16.66 = 16,7
Percent means in hundredths. Imagine a number as a circle (or a pie) divided into 100 slices. One slice is one percent of that number. In the given problem we are told that 3 = 18 slices of the number you're looking for. So how many chunks of 18 slices are there altogether? Count them up (=5 2/3 chunks). Each chunk is 3, so multiply by 3 and there's your answer!
Prolific math teachers does make a significant difference!!!
I never considered using Basic algebra. Thanx
Percentages are used everyday in finance. Extremely important subject.
Another approach could be realising, that 18% of x is the same as x % of 18. Then dividing 3/18 to 1/6 give you 16.6 periodically....
Very good as always. Thank you.
I always multiply first and then divide.
What is the name of the blackboard software you're using?
I got 16.6666666 as I divided3/18= 0.166666 which -1%. Multiply by 100 =16.666 recurring.
If I'd ever had a maths teacher who waffles as much as this, I'd never had learned _anything_
IKR?!
Let me number be x
Then 18% of x=3
I,e 18x/100=3
By solving,
x=3×100÷18
x=50/3=16:6
As simple as above.
10 second answer:
If 3 is 18%, then 3 divided by 18 is 1%.
So 1% is 0.1666.
Multiply 0.1666 by 100 to get 100%.
18% v 18/100 : 3divide by 18% : 3/18/100. = 3X100/ 18: 300/ 18=16.666. Percentage I do by hundreds, that way you can visualize without pencil and paper and calculator the answer I would say orally
If the explanations were to the point and the fluff less verbose…I would watch more !!
Why don't you use cross multiply more. I took algebra as well but wr still learned cross multiply in grade school.
I'd do a proportion kind of method:
18% ≡ 3
1% ≡ 3/18
100% ≡ 3/18 × 100
That's exactly how I'd solve it.
However I would explain it like this:
Question
18% of what number (x) is 3?
Solution:
Find 1% of the full amount. I.e. (x).
To do that, take the 3 (which represents 18%) and divide it by the percentage it represents. In this case 18.
This results in 0.16667 and tells us that this is 1% of the full amount (x).
So to find out the full amount (x) (or to put in another way; 100%), you just multiply 0.16667 by 100.
And you'll have your answer.
It's a somewhat more long-winded explanation, but it gives the reason behind the method. Which I think is important.
@@shabazzy Yep I fully agree with you.
Simple, just divide 3 by 18% (0.18) and you will get 16.6667... to check what you get, simply multiply 16.6667 with 18% (0.18) and you will get 3.00006 or 3... correct!
Don’t you think an example that used whole numbers might be less confusing? Just asking. This should have been a 10 minute video, at most.
I think the OP is trying not to make it too easy. But in real life, often things don't work out to be whole numbers. The challenge is, can you break the problem down to be whole numbers? If you have 18%, you can tell that's easily divisible by 3. And 3 is easily divisible by 3. So right away you have 6% (of some number) = 1. In my mind, this is closer to whole numbers and easier to deal with. Would you agree?
David, I think your comment is less than helpful.
Percent quiz: If this guys takes out the phrase "you know" , the video length will be reduced by ____ percent.
Maybe he's been talking to phoney Tony Blair too much.