He is teaching for those who don’t know or don’t remember. I don’t see why the criticism, if you don’t like it then don’t watch it. I enjoy his classes and always learn something. Thank you John for sharing your knowledge 👍🙏
@@scotthunt7077 Yes, I have noticed that some people sadly act extremely rude and become a joke, by criticizing the teacher and trying to teach the teacher. They tend to forget that this is Mr John’s CZcams channel and his hard work and time. They look so jealous and selfishly ignore the fact that there are plenty of other people like us, who appreciate Mr John’s hard work. I really don’t know why they don’t start their own CZcams channel to display their own work, without visiting this channel to display their bullying behaviors.
@maxwellsmart8730 Yeah, it's easier that way, though your description is insufficient for someone who don't yet understand the LCD, you need to see all the parts of the whole process, how you proceeded when you "multiplied the denominators and numerators". Multiply each fraction by the denominator of the other, you get two fractions with the same (common) denominator, which, here, is not the least. Add them up, and proceed to divide the resulting fraction by 2 or 3 or 5 or any obvious number you can find, stop when you find a prime number, a number is divisible by 3 when the sum of its digits gives a 3, or a number that divides by 3, if unsure, repeat the process, until you reach a prime, 3 or otherwise, then you know (9834854 = 9+8+3+4+8+5+4 = 41 = 5). (hoping the column spacing shows correctly) 3 1 3x8 20*1 24+20 44 11 (prime) -- + -- = -------- + -------- = ----------- = ---- = --- 20 8 20*8 20*8 160 160 40
@@francisdelpuech6415 Not sure if you are talking to me or to Maxwellsmart8730, but we both end correctly with the LCD, 40. We just used a faster method to do so. That's our point, I just elaborated a little more trying to help. You are confused, there is no such thing as a HCD, try and find it if you can, maybe you mean HFC (highest common factor), or GCD : "The largest integer d such that D|A (D can be divided by A) and D|B is called the greatest common divisor of A and B". ("|" means Divisibility : if D and A are two integers, D|A means that D divides A evenly). Greatest Common Factor (GCF) : the largest number that divides evenly into each number in a given set of numbers. Least Common Multiple (LCM) : the smallest positive multiple that is common to two or more numbers (to find the LCD, you will have to find the LCM of the denominators). Also look at : Highest Common Factor (HCF), Greatest Common Divisor (GCD), Greatest Common Measure (GCM) and Highest Common Divisor (HCD).
I learned this when we studied prime numbers. So we factor each denominator in prime numbers. 20=2^2 times 5. 8=2^3. Then you take ALL the prime factors with the highest power so 2^3 times 5=40. That’s your LCD. 😊
I define LCD slightly differently than most. I used 20 as my LCD, with gave me 3/20+2.5/20=5.5/20, multiply by 2 to get 11/40. That's easier if I see 2 numbers (like 20 and 8) that have a fairly easy number as a common denominator that is not a whole number.
I multiplied the denominators, cross multiplied numerators added the fractions to 44/160 and reduced. But I am going to use his steps on the more difficult numbers he had in the example..
11/40 is the answer. To find the Least Common Denominator (LCD), of 40 and 8, first factor 40 into its prime factors which are, 2 × 2 × 2 × 5 = 40. Next, factor 8 into its prime factors which are, 2 × 2 × 2 = 8. Finally, because 8 has three prime factors of 2, multiply these by 5 which is a prime factor of 40. The prime factors of 40 are, 2 × 2 × 2 × 5 = 40.
John is teaching those who don't know this. We old farts learned the skill back when dinosaur toenails were used for chaulk and do this in 5 seconds not even needing to think about it. We are not John's focus. You only have to watch the class if you don't know how to fast forward.
@@terry_willis great idea. He repeats an introduction each time f9r newcomers. Often I just enjoy the thumbnail, solve the problem and don't view the video, or advance to the end to confirm my solution. But listening to John's teaching technique could help parents to help their kids learn math. John's technique is a close match to mine.
Solved in my head at the thumbnail, my answer is 11/40. The LCD of 3/20 and 1/8 has to be 40, since 20*2=40, and 5*8=40. Therefore, 3/20 = 6/40, and 1/8=5/40. Add the two: 6/40 + 5/40 = 11/40, and since 11 is prime, and not a factor of 40, we can't simplify further, so we're done!
@@rebeccadee4107I think he’s missing how to get 40. “Has to be” doesn’t explain how you get it. I know, I know! When you are so used to do it you just do it mentally but you need to explain how you get it. 😊
I think you made it too complicated. I found the easiest way to teach the LCD is to either multiply the denominators or, even easier, number lines in factors to each denominator. When they match up, bingo, the LCD.
I get the second method, but how does multiplying the denominators teach LCD? If you multiply the denominators here you get 160, which isn't the LCD at all.
@@gavindeane3670 if you multiply the denominators you have a common denominator, then multiply each numerator by the new denominator, this will give you a new numerator. now you have two like fractions with the LCD. 3/20 + 1/8. multiply the two denominators 20 x 8 = 160. now divide the new numerator (160) by the old numerator0 each numerator by 160, which will be your new numerator. 160 / 3 = 24 so 3/20 = 24/160 do the same for 1/8. 160 / 8 = 20 so 1/8 = 20/160. so now the equation becomes 24/160 + 20/160. reduce the fractions. 44/160+20/160=44/160 reduce the fraction 44/160=11/40. therefore 3/20+1/8=11/40.
Finding the LCD is a useless skill. Any common denominator will do the job; just complete the addition and reduce the fraction. Obsessing about the common denominator being the least possible value is an unnecessary distraction and obstacle.
No A+ for you. Try again. The LCD or Least Common Divisor is "1" Factors of 20 are 1,2,4,5,10,20 Factors of 8 are 1,2,4,8 Common Factors are 1,2,4 The LEAST common factor is ONE --- I was BS Math from a public college --
He is teaching for those who don’t know or don’t remember. I don’t see why the criticism, if you don’t like it then don’t watch it. I enjoy his classes and always learn something. Thank you John for sharing your knowledge 👍🙏
Totally agree with you.
@@scotthunt7077
Yes, I have noticed that some people sadly act extremely rude and become a joke, by criticizing the teacher and trying to teach the teacher.
They tend to forget that this is Mr John’s CZcams channel and his hard work and time.
They look so jealous and selfishly ignore the fact that there are plenty of other people like us, who appreciate Mr John’s hard work.
I really don’t know why they don’t start their own CZcams channel to display their own work, without visiting this channel to display their bullying behaviors.
Very well said
But useless... What criticism anyway ("extremely rude" ?), I don't see anything worth responding to ! GET OUT OF HERE !
I did it a little different. I multiplied the denominators and numerators and got 24/160 + 20/160 =44/160 and reduced the fraction to 11/40.
@maxwellsmart8730 Yeah, it's easier that way, though your description is insufficient for someone who don't yet understand the LCD, you need to see all the parts of the whole process, how you proceeded when you "multiplied the denominators and numerators".
Multiply each fraction by the denominator of the other, you get two fractions with the same (common) denominator, which, here, is not the least.
Add them up, and proceed to divide the resulting fraction by 2 or 3 or 5 or any obvious number you can find, stop when you find a prime number, a number is divisible by 3 when the sum of its digits gives a 3, or a number that divides by 3, if unsure, repeat the process, until you reach a prime, 3 or otherwise, then you know (9834854 = 9+8+3+4+8+5+4 = 41 = 5).
(hoping the column spacing shows correctly)
3 1 3x8 20*1 24+20 44 11 (prime)
-- + -- = -------- + -------- = ----------- = ---- = ---
20 8 20*8 20*8 160 160 40
LCD means Lowest Common Denominator. Yours is HCD, Highest Common Denominator!😊
@@francisdelpuech6415 Not sure if you are talking to me or to Maxwellsmart8730, but we both end correctly with the LCD, 40. We just used a faster method to do so. That's our point, I just elaborated a little more trying to help.
You are confused, there is no such thing as a HCD, try and find it if you can, maybe you mean HFC (highest common factor), or GCD : "The largest integer d such that D|A (D can be divided by A) and D|B is called the greatest common divisor of A and B". ("|" means Divisibility : if D and A are two integers, D|A means that D divides A evenly).
Greatest Common Factor (GCF) : the largest number that divides evenly into each number in a given set of numbers.
Least Common Multiple (LCM) : the smallest positive multiple that is common to two or more numbers (to find the LCD, you will have to find the LCM of the denominators).
Also look at : Highest Common Factor (HCF), Greatest Common Divisor (GCD), Greatest Common Measure (GCM) and Highest Common Divisor (HCD).
I learned this when we studied prime numbers. So we factor each denominator in prime numbers. 20=2^2 times 5. 8=2^3. Then you take ALL the prime factors with the highest power so 2^3 times 5=40. That’s your LCD. 😊
He is a great teacher
got it i my head.
Me too
I define LCD slightly differently than most. I used 20 as my LCD, with gave me 3/20+2.5/20=5.5/20, multiply by 2 to get 11/40. That's easier if I see 2 numbers (like 20 and 8) that have a fairly easy number as a common denominator that is not a whole number.
3/20 + 1/8
Least Common Denominatior : 40
6/40 + 5/40 = 11/40
Answer: 11/40
Instantly visualized it as 11/40. Not sure if it got factored or trial and errored in the process.
I multiplied the denominators, cross multiplied numerators added the fractions to 44/160 and reduced. But I am going to use his steps on the more difficult numbers he had in the example..
11/40 is the answer.
To find the Least Common Denominator (LCD), of 40 and 8, first factor 40 into its prime factors which are, 2 × 2 × 2 × 5 = 40. Next, factor 8 into its prime factors which are, 2 × 2 × 2 = 8. Finally, because 8 has three prime factors of 2, multiply these by 5 which is a prime factor of 40. The prime factors of 40 are, 2 × 2 × 2 × 5 = 40.
The original denominators were 20 and 8, not 40 and 8. Cordially 😊
You're absolutely correct. The original denominators were 20 and 8. Thank you for correcting my error. My bad. My very bad. OOPS.
John uploads more algebraic problems than God can solve. :) Great job.
Got it 11/40.
Simple LCD.
20 and 8 is 40 LCD.
Thanks for the fun.
20 = 2×2×5
8 = 2×2×2
LCD = 2×2×2×5
= 40
3/20 = 6/40
1/8 = 5/40
Total = 11/40
VERIFY
(24+20)/160
44/160
22/80
11/40✔️
Talk about beating around the bush. I did this in my head in 20 seconds then scrolled to the end to see if YOU had the right answer. You did.
John has "the gift of gab". Or as some might say the gift of blab.
John is teaching those who don't know this. We old farts learned the skill back when dinosaur toenails were used for chaulk and do this in 5 seconds not even needing to think about it. We are not John's focus. You only have to watch the class if you don't know how to fast forward.
@@richardhole8429 When I listen to John's full lecture I use speed 2X - he speaks slowly and 2X is very understandable to me.
@@terry_willis great idea. He repeats an introduction each time f9r newcomers. Often I just enjoy the thumbnail, solve the problem and don't view the video, or advance to the end to confirm my solution. But listening to John's teaching technique could help parents to help their kids learn math. John's technique is a close match to mine.
Bahahaha! Me too.
For 5 and 3, what would the greatest common multiple be? Would it be 5^♾️ times 3^♾️
Many times I just skip the LCD and just cross multiply and reduce. I was able to easily do this one due to easy numbers.
With these fractions, it's easier to take a shortcut.
3/20 +1/8 =
0.6/4 + 0.5/4 =
1.1/4 =
11/40
2÷/20.....8
-------------
2÷10........4
-------------
2÷ 5.........2
-------------
5÷5...........1
1...........1
2×2×2×5=40 is the LCD.
Answer is 11/40.
11/40
Solved in my head at the thumbnail, my answer is 11/40.
The LCD of 3/20 and 1/8 has to be 40, since 20*2=40, and 5*8=40.
Therefore, 3/20 = 6/40, and 1/8=5/40.
Add the two: 6/40 + 5/40 = 11/40, and since 11 is prime, and not a factor of 40, we can't simplify further, so we're done!
Best example, thank you.
@@rebeccadee4107I think he’s missing how to get 40. “Has to be” doesn’t explain how you get it. I know, I know! When you are so used to do it you just do it mentally but you need to explain how you get it. 😊
I learn in school L.C.M. means lowest common multiple.And H.C.F. means highest common factor
Thank you
For 5 and 3, what would the greatest common multiple be? Would it be 5^♾️ times 3^♾️?
The point here is the LCD not GCM
0.275
Worked it in my 85 year old head. Twas easy.
Nice review
11/40.
LCD =/40
3/20 = 6/40
1/8 = 5/40
13/15
1/2
these are fun. im such a nerd.
👍👍
That was easy mental maths.
Is he talking about Liquid Crystal Displays??
11/40 ?
11/40 or .275
My answer is 11/40
The answer is 22/80.
I thought the hippies did LCD back in the 60s 😂
1/20
Unless you never had fractions in your life this is simple.. but a good observation anyway
I think you made it too complicated. I found the easiest way to teach the LCD is to either multiply the denominators or, even easier, number lines in factors to each denominator. When they match up, bingo, the LCD.
I get the second method, but how does multiplying the denominators teach LCD? If you multiply the denominators here you get 160, which isn't the LCD at all.
@@gavindeane3670 if you multiply the denominators you have a common denominator, then multiply each numerator by the new denominator, this will give you a new numerator. now you have two like fractions with the LCD. 3/20 + 1/8. multiply the two denominators 20 x 8 = 160. now divide the new numerator (160) by the old numerator0 each numerator by 160, which will be your new numerator. 160 / 3 = 24 so 3/20 = 24/160 do the same for 1/8. 160 / 8 = 20 so 1/8 = 20/160. so now the equation becomes 24/160 + 20/160. reduce the fractions. 44/160+20/160=44/160 reduce the fraction 44/160=11/40. therefore 3/20+1/8=11/40.
Finding the LCD is a useless skill. Any common denominator will do the job; just complete the addition and reduce the fraction. Obsessing about the common denominator being the least possible value is an unnecessary distraction and obstacle.
Obviously 4/ 28
😂 you’re joking!!!
No A+ for you. Try again.
The LCD or Least Common Divisor is "1"
Factors of 20 are 1,2,4,5,10,20
Factors of 8 are 1,2,4,8
Common Factors are 1,2,4
The LEAST common factor is ONE
--- I was BS Math from a public college --
Just kidding to see if anyone thinking for yourself of just accepting my BS
Hee Hee
You can thank AI for changing my typed "or" into "of". Perhaps this may be why AI is called "Artificial" Intelligence.
👍👏🙏💪😎🌎❤️
too much scribbling on the screen
How does he know that most don’t understand the LCD? Maybe in USA, but …😂
Thank you
11/40
11 / 40
11/40
11/40
11/40
11/40
11/40
11/40
11/40
11/40