Fast Mental Multiplication Trick - multiply in your head using base 10
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- čas přidán 20. 06. 2024
- This mental multiplication trick uses the idea of a third number - a base number - to help us multiply two numbers in your head. This series of videos first looks at multiplying numbers near 10 using base 10. The second video looks at multiplying using base 20 and 30. The third video looks at how to apply this mental multiplication trick to numbers near 50. The forth video the investigates ho to easilt mentally multiply numbers near to 100. Continue your mental math multiplication abilties here!
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Schools teaches memorization. This guy just taught me how to save time while still using my brain and avoid using a calculator. I just learned something so useful in like 2 minutes meanwhile in school it takes years to learn something that you'll actually use in your life
Still takes memorization LOL
@@richiejourney1840 yes but easier lol
schools teach useless "memorization" that you never memorize. and they know it.
I didn't pay attention when I was in school either...
👏👏👏❤️
I'm 65, and a little over 10 years ago, I was diagnosed with dyscalculia, which is a math specific learning disability. If only I had known this as a child, I would have felt a lot better about not getting math! But, your explanations also make more sense than any I remember in school! Thanks!! I'm watching math without breaking out into hives!!🤔😂😂👵
really sad
Super sad
Not sad at all
i’m so proud of you, ma’am! i’m glad you’re being able to understand math now ❤️
Really Super sad
Where's them math at?! Not scared of you anymore!
Now I can pass this on to my grandkids. I'm gonna sound like a genius.
YES! Thank you very much.
Learn it by high school and a few big words, you know bigger then the 4/5 letters that are in every sentence these days, and people will think your smart/intelligent for the rest of your life. Tricky, tricky. Just be casual about it. Throw in occasional comments like “caught thinking outside the box again” or shrug your shoulders when asked how you do that. Or, offer to teach them. I’ve fooled people for 50 years. After awhile people just assume.
I have to express my gratitude to you for all that I've learned from your teaching videos. I deeply appreciate the relaxed pace and concise yet easy techniques you employ. I have suffered for years from a deep anxiety regarding math. My mind locks and my thought process borders on paralysis when it comes to calculations. Thanks to your vids, that is no longer the case. I can't express adequate thanks to you.
You are definitely not alone in feeling anxiety about math! Math, in general, gives me anxiety, but especially having to do calculations in my head and on the spot!
Idk if there’s a “math equivalent” to the reading disability of dyslexia, but I can’t help wonder if there’s a similarity beyond their comparative nature in being “learning disabilities.”
I have very little problem when working math problems on paper (or calculators or course), but the minute I’m asked to visualize a math problem in my head, I blank out or “lose my place” as I call it, and end up even more flustered and anxious as I search for a pencil and paper. It’s almost like the part of my brain that requires envisioning numerical symbols is missing or blocked, much like the dyslexic person’s eyes and brain do not connect when deciphering letters in order to read.
Anyway, the feeling of paralysis you mentioned feeling hit the nail on the head!
@pundoorasbox7485 I also appreciate your transparency re: your own anxiety. It's a bit of a stigma when you feel intellectual paralysis
Fascinating but my calculator might feel rejected
Well let it rest sometime I think it needs it.
Lol
😂😂
😂💀
Your calculator is the reason you're a grown up watching videos on how to multiply 2 digit numbers.
amazing, im learning more in 1 hour on your youtube than i did throughout all of my schooling life.
true.
Well you're not...
how?
@@gamershunch2099 because he's been binge watching this guys videos? Also I think he means the stuff he remembers from school, not what he learned
@@anjellalo972 he should have paid a little more attention
I really struggled with maths at school, and managing to get ungraded in my maths exam, fast forward 40 years to now and I can confirm my confidence has 100% grown
What the hell?!
All the way through high school and 5 years at uni and I never was shown this technique?! 🤯
It's so simple and intuitive!!
I'm actually kinda angry I was never shown this at school.
17x15 = (10+7)x15=150+105=255
That’s what they taught you! Way better to remember
My god this is brilliant. My middleschool class is gonna love this. Thanks!
cool
I’m in middle school to
It’s just distribution. 14*13 in his method is just (10+4)(10+3) he just writes it differently
jalle88 you’re in high school now
@@isaiahjamesimmakingthiseas8018 ...I'm pretty sure that was a teacher, mate.
Why are we not taught this in school??? Freaking genius
Check this out czcams.com/video/qCppoqqSbts/video.html
Because it isn't typically useful to know how to do this. The method taught in school is slower, but more comprehensive, and teaches and understanding of what is going on (specifically the distributive law of multiplication over addition and subtraction)
@@aaronwarwick9966 Well, when youre little and first learning multiplication I dont think itll be a good Idea to teach this, but It might be a pretty good idea to teach it to students who already understand multiplication. Like teach it to an 8th grader or something.
@Aristides Gonzalez Did you ever find the use in later life for Algebra?.
you are being teach this at school.
You learn to calculate (a+b)(a+c)=a*a+a*(b+c)+b*c
with 14*12, a=10, b=4 and c=2 so that gives you 10*10+10*(4+2)+4*2=100+60+8=160+8=168.
That's it
Pretty cool trick. I've always used the method of splitting the multiplication into 2 easier ones and it worked fine for 30 years and counting: 15 x 13 = 15 x 10 + 15 x 3 = 150 + 45 = 195
This is also how I do it.
many years ago ..my father taught me this splitting trick
I do the same
15x13... 15x15 - 30
Awesome!
This reminds me of the time when I was multiplying numbers out loud and broke down one of the numbers to make the multiplication easier and someone at the same table was surprised you could do that.
If school did a better job of explaining how basic math worked, they could easily teach simple tricks like this to speed up mental arithmetic.
Why the heck don't we learn this in school?
Coz teachers don't want to get embarrassed by us getting the answer before he gets the first digit
Hive Atlas Because they want you to learned the basics ways thats been handing down to us for 1000 of years.
But i would like an explanation about why that works...?
Mike McCarthy
Cavemen Style
That's so true
The reason behind that is that they just teach u whats in the book that the government gives for schools so they don't teach u the exiting and easy ways to do it.
I have always been truly appalling at multiplication - this is revolutionary for me. Thanks so much!!
Brilliant! I've had to brush up on math skills for an aptitude quest and your series of videos have helped immensely.
I seriously should’ve been taught this in elementary school. I learned more in 10 minutes than I did in 3rd, 4th, and 5th grade.
hey there, please be kind and help.….iam now 7th grade , i fear my study a lot bcoz i mostly depend on memorization,
i barely can use logic or i suckk, i am not good at other subjects except math....i love math its fun as i am killing and torturing monsters in game.…
so..… is it okay if i learn these genuine knowledge besides my studies
@@emiyakiritsugu6329 hey don’t worry you are in 7th grade only. It is okay to learn this kind of stuff
@@_aaryanmore thanks for telling,
🤤
@@emiyakiritsugu6329 let me tell you right now. It is okay to learn for fun but DO NOT SUPPLEMENT THIS FOR UNDERSTANDING OF MATHEMATICS. Tricks don’t lead you anywhere. At that point you are computing like a computer. As u get into higher level math many idiot teachers will try to get you to memorize things without explaining the reasons why they work. The same applies here. It’s okay to have fun or have this as a party trick, but unless you understand the fundamental reasons behind it, you should never use this as an alternative.
@@SortaFresh iam gonna cry 😱😨😭from your huge pressure
but i dont use this trick for anything but iam bored in lockdown so i learn this bcoz i want to do this in my head otherwise i will do it in general way
thank u for scolding me , it took u forever to type
Please continue on what you're doing, do not stop! Its really helpful thank you
We need more people like you in our society. Keep up the good work.
Everyone: Eight
Tecmath: Aight
HAHAH
I'm 38. Speechless to say the least. Found this video after researching math teaching materials to help my teenage daughter. Now I know I'm the one benefiting from it. Beyond thankful, man. Cheers from Brazil.
I have no words to explain how much your videos help me, thank you.
Awesome Video! I'm going to share this with my children. I've always done this using multiples of 10. Like for 14x12, I'd calculate 14x10 and add 14x2 to get 168. Your way is easier. Thanks!
I’ve done this my whole life without being taught this, it always seemed easier to me to work out equations this way.
Can I ask, why it works? Like I understand how to do it but why does this tactic work
@@Rose-oz6lt
Ill try to explain it for you. I suggest a pen and paper because this proof is hard to explain in words.
Let’s use the example of 56 x 48 = 2688
In this alternative method this would become 54 x 50 +(-18)
Let’s turn turn this method into algebra
Normal way of multiplying is F x G = H (Equation 1)
In this alternative, you use a ‘Base’, which ill call B
In this alternative method, You find the difference ( for F the difference is D and for G the difference is E) between the Base (B) and your numbers (F and G). If ‘ F=B+D and G = B + E, then B = F - D and B= G-E (Equations 2)
Now we have two equations that both equal the same value, which is B, we can make them equal each other:
F - D = G - E (Equation 3)
Rearranging
F + E = G +D (Equation 4), this equation he says in words at 2:12 to 2:25
With some more rearranging G = F + E - D
Now lets bring our original equation F x G = H and lets combine with our previous equations:
F x (F+E-D) = H
If we Expand: F^2 + FE - FD = H. (Equation 5)Remember this equation as we will come back to it.
Now using the method. The first step is to do Equation 4 so lets use F +E (In this example 56 +(-2) = 54 )The second step is to use the Base (In this example is 50) Which we know, in equations 2, is equal to F - D. Let’s multiply these together:
Algebraically: (F+E) x (F-D). Expand the brackets, F^2 +FE - FD - DE = Some value (Equation 6)
In this example: 54 x 50 = 2700
Now realise something? Equation 5 and Equation 6 look similar. The only difference is the Equation 6 has -DE and Equation 5 doesn’t.
What is the last step? ADD DE to equation 6, thus making it equal to equation 5.
That is the proof.
@@theracingpotato3124 shouldn't it be 54×50 minus 12 for the alternative, not 54x50 +(-18)?
I have a nephew who hates math because he says it's too difficult. I love math because I was lucky enough to have an excellent math teacher who made learning math fun. You remind me of my math teacher. I am positive that once my nephew watches this video he won't hate math anymore. Thank you 💕
Thank you so much for taking your time to make this incredible and eye-opening video!
Thank you - your videos are making our "Math Year" homeschooling much easier.
Such a fantastic series! I’m very thankful for this. Thank you!!
I can’t even believe I found this channel! I feel like I just won the lottery! Math has never been my top subject ~ and here at 40 years old, I now have a way of where I can solve multiplication problems in my head!
Thank you for sharing your knowledge ♥️🙏🏼
Orlando Florida
I can't believe I have never heard of this before in my life!! Thanks so much!
I absolutely love this! How long have I been searching for such a system? Years!
And yet it was just a few keystrokes away.
Thank you tecmath! You are AMAZING! Your website makes fundamental maths a pleasure.
Where have you been all my life🤦♀️......thanks alot!!
Secret is to know your times tables inside out as we were taught years ago in school what a great channel ive found 👩🏼🎓
Thanks a lot!!! My maths was so poor but u brought me to the light and now I love maths!!!!
I'm 39 years old and only learning about this today. Thank you for being an awesome teacher.
Yesterday, I had a 2-hr drive home. Spent most of the ride mentally working this method in my head with random problems and checked results with Siri on my watch. Funny how time flew. I was thoroughly entertained! With practice, it becomes easy to immediately get that 10x without any real thought, and also easy to instantly generate the product of the two "more than / less than" numbers without much thought. The longest part is the final addition / subtraction.
"What is 14 x 12?"
I am immediately lost.
14 x 10 , add 2 more 14's. 140 + 14 + 14 or 140 + 28 = 168
Using base 10:
14×12
14 is 4 more than 10.
12 is 2 more than 10.
4. 2
14×12
So, 14+2 (or 12+4) = 16
Add 0 to the end, making the number 160.
Then, multiply 4 by 2, which equals 8.
Finally, add 160 to 8, which equals 168.
I hope this helps. :)
For his “8x17” simply 8x10=80 then just 7 (from the 17) multiple by 8= 56+80
@@@td5604 I really love you saving me from big headache =)
@@DiepNguyen-ce4hq You are welcome! :)
Thank you for sharing this techniques. It helps improve my skills in math. :)
I want to thank you so much for this SIMPLE method, I suffer from mild dyslexia & im not a wizard in multiplication or division, I couldn't figure out for the life of me how I could do every other piece of math in the book in different areas yet my memory wasn't wired to deal with neither operation (im in my 2nd year of college). It was how I was trying to handle it, outgrowing lattice, & tired of the egyptian math, so again I want to thank you not just for me but for ALL OF US because there are soo many of us that feel inadequate being some kind of smart yet having issues handling these two operations. Its truly a blessing to share it regardless of the history behind it! :-)
Dslexia is a myth there is no such thing its all n our head
Your videos have changed my life. Thank you so much.
I loved your maths and it really helps with my multiplication at school!! THANKS!!!
I felt smart at the beginning of this video then I got lost in the middle of it lol
I think I need to do more practice!
Your better than all my school teachers stuck together!And these tips and tricks are really useful
5 minutes into the 1st video, and already this has helped me! Thank you!
This is amazing! So helpful. I never was good at mental math in multiplication now I am. Thank you.
THIS IS AMAZING MAN!!!
THANK YOU SOOO MUCH
PLEASE DONT STOP!!!
thank you so much for this video, you're awesome.
This is the best trick i’ve found and i’ve tried some before! Thanks!
Unbelievable. You make it so easy! I wish schools could teach the way you teach us
Life saver, thanks so much!
It was very much helpful .
Thanks a lot .
Thanks so much this is really helpful!👍🏼
I’m grateful for you! Thank you for sharing and teaching!
I have to say, I'm pleasantly impressed. At first I was skeptical of what kind of method would be presented, since the numbers were pretty low, but the method seems legit. I wasn't content however with not understanding why this works, and I think you really should explain. I deduced where this came from myself using algebra, and I'm not sure if this is how you did this but:
(10 + a)(10 + b)
100 + 10a +10b + ab
10(10 + a + b) + ab
Above is how I derived the method. If you notice, a and b are the second digits of each number, or what you take away if the numbers are below 10. So the first step in the videos is (10 + a) + b followed by 10 times that and adding to ab.
I may be wrong, but dissatisfied by just 'doing' it I tried to find out why and this is what I found. Some may think this isn't a big deal and is just teaching kids to memorise and not think about what they are doing, however I think that understanding why this works, whilst may not concern anything of importance in Mathematics, has a beauty in its own purpose, as it demonstrates how manipulation of numbers can lead to different pathways to solutions. But only with the explanation!
it is very fun.new for me although I knew some stuff before.keep on techmath...
thnx!
Wow just wow. You just taught me something I haven’t been able to get my head around for 13 years of education in the first 2 minutes of your CZcams video just wow
My son used Kumon for math and it's his favourite topic and when I was working with him I always used to find 'tricks' to do math. I was adamant that there was always a 'trick' to math.... you just needed to find it.
Your videos are amazing and I'm only frustrated that I've only just disovered this channel.
Just subbed!
Kyle W Baker says it all for me,,,, I was the mathematical DUNCE in elementary school. If I had just been shown the puzzle business the application would have come easier much later. Between the accent, cool laid back manner, and the clear drawings this guy could drag me to mathematical Hades and back and I would be happy
Thank you sooooooooo much this really does help. I am still practicing so i will hopefully be much faster. Thanks and keep up the good work!
Thank you so much! ♥️ You have no idea. I was traumatised as a child, sometimes physically, because it was drilled into me that I’m a nobody if I can’t calculate.
I made sure I never did the same to my kids and now they thrive.
This has helped me immensely and made a joy of maths. Thank you 🙏 😊
This is fricking cool. Thank you so much tecmath.
thankyou...coz of u i could improve my skills!
thank you so much for this
Where were you when I was in school?
This is so practical and easy that it is shocking.
Can't thank you enough.
This makes learning mathematics interesting!! Thanks 🙏🏻
I love this video thanks techmath!!!
Erik Campos q
I was thinking this was clickbait, but it really is a ridiculously good multiplication algorithm!
Fascinating work with numbers. Thanks
Brilliant method ... Very very well explained. Thanks ... A lot of kids will fall in love with math after watching these videos.
Thanks Alot Mate This Realy Helps me out in School
I LOVE YOUR CHANNEL
This is amazing, honestly a life saver.
Wow thank you! I have watched a few others on this, but I really like your method! I will definitely be using it in the future!
Amazing trick! Some people call it "the distributive law" though. I don't know if people generally talk about that at school..
thank u so much man
you are a genius i hope that good things happen to u☺
What can I say except you're AWESOME!
Thanks for this ...wow should be taught this way for sure...looking forward to progressing up the levels!
This is called Vedic math. India and England are practicing this for a long time!
Why isn’t my teacher like this! This video is life saving
This is great - thanks for sharing. I wish I had teachers like you when I was at school.
looking at your videos to mentally prepare for MEPS and you are VERY helpful. Keep up the awesome teachings!
I’m learning this too to take the ASVAB… I’m so bad at division and multiplication in my head.
Lmaoo I thought I was the only one, I'm actually taking the ASVAB practice test and I'm doing terribly at math but these videos are helping me a lot. Hey which branch did both of you join? If you even see this comment lol.
The more I learn about math on CZcams in my post-college graduation life, the more I realize that our math teachers probably didn't care that much about actually teaching us.
man im in calc 3 rn and i feel like im retarded since i didn’t know any of this
Wow.. took 41 years to discover this. Damn school is a wsste!
The last math trick blew my mind this one +10 is even more awesome 👏🏼
Thank you so much for this it makes perfect sense to me and i grew up hating math now I'm starting to love it.
I usually use this for 15x13
14 squared - 1 squared
But this method becomes complicated when the numbers are far apart. Thanks for your method ;)
OMG U HELP SO MUCH. I THINK OUR TEACHERS ARE PART OF A SECRET EVIL SOCIETY TO TORTURE OUR BRAINS. WHY CANT THEY TEACH US THIS
Shadow 88 teachers don't know much. all they know is if someone's feeling get hurt or if you're a racist.
Curriculum.
Yo
mjcard not sure they even know that
Only if they follow the syllabus that they're taught! Which is why my mother got fired she never followed what they told her, as a teacher and happened to be one of the greatest not only special education but honor classes for 8th graders, she gave all students inspiration to understand learning she was very creative and everyone loves it
Getting ready for the PSAT, and I need these methods for fast solving. Thank you!
This is excellent. Thanks for sharing.
who would dislike this? this is amazing!
Liked the comment ;)
thnx :)
people who don't understand math XD
makes sense
Try Donald Trump !
i feel 10× smarter XD thxxxx soooo muchhhhhhhhh who else feels this way?
@Jacob Zhou dang
I feel epic
Xd is cringe
I dont care If you asked or not
are you sure it's 10x smarter or 12x times smarter ?
@@martinkuliza 😂
OMG, THANKS SO MUCH! THIS VIDEO IS SO USEFUL! WHY DONT WE GET TAUGHT THIS AT SCHOOL? UR AMAZING!
your videos are helping me get my GED awesome work!!!
Wow...just awesome. This is hands down the best math channel/lessons I have ever seen. I had so much fun doing this. Really - this is a true service to math literacy.
Bob Ross is back to tackle math!
I can't believe it was this easy! I'm going to watch more of your videos.
I usually tried to apply the binomial theorem in my head, but this method is WAY faster!
Nice! It's also interesting to think through the algebra of why it's answers are correct.
This trick is awesome and I'm in 4th grade! I'm sure I will get good grades in Math
Lucas Games2193 There will be more to it once you go to middle school and high school. Everything won't be just multiplying numbers. But it's still a good idea to know how to do this.
this is the first time ive heard of this. Ive shouldve known it when I was WAY younger
This boy just learned how to math he's not suppose to know for another two years in his head. Why are you criticizing him? It seems to me as if he has a+ parents if instead of looking up dumb youtube videos he's learning maths and being passionate about them. You're getting riled up by a 9 year old.
ten tor let a kid be a kid
lol lol Lol n 6wtyck4n
what he is actually doing is writting:
(a*b) = (10+X)*(10+Y) = 10*Y+10*X + X*Y + 10*10 = X*Y + 10*( [X+10] + Y ) = X*Y + 10*( a+ Y)
or if you add the 10 to Y, you will get: X*Y + 10* (X+b)
However I find easier to do the other way (since adding 100 is always much easier):
10* (X +Y) + X*Y + 100
So for example if you have:
14 * 15 .... X=4, Y=5:
10*(4+5) + 4*5 +100 = 190 + 20 = 210
This idea can be done in other "bases" if you call it that way... instead of writting a=10+X, b=10+Y , you can write a=100+X , b=100+Y
the result will be almost the same:
10000+ XY + 100*(X+Y)
base*base + XY + base*(X+Y)
So in base 20 an example would be: 25*26 = 20*20 + 5*6 + 20*(5+6) = 400+30 + 220 = 650
an example containing different "bases" (1000, 300, 100 respectively):
1371* 1420 = 1000*1000 + 1000*(371+420) + 371 * 420
371*420 = 300*300 + 300*(71+120) + 71*120
71*120 = 100*100 + 100*(20-29) - 20*29 = 10000 - 900 - 580 = 8520
going up:
371*420 = 90000 + 300*191 + 8520 = 90000 + 57300 + 8520 = 155820
going up
1371*1420 = 1,000,000 + 791,000 + 155,820 = 1,946,820
Chris X Thanks very much for posting this. I'm less interested in learning arbitrary "tricks" to solve problems, and more interested in learning the real math behind the tricks. This was exactly what I was looking for. All I was taught in school growing up was to memorize patterns to solve problems, like those in the video. But you never learn WHY you're doing it.
The way you've shown can be customized based on different problems and shows more of an understanding with manipulating numbers. Thanks again.
I agree. Thanks also.
Lol your way is far to complicated and not practical...fail
Troll God said a the dumb face.... keep on whining for some attention! common! you can do it!!! beg and lie on your knees..beg for more.
Troll God it's actually not
Thank you for sharing this trick with us.
Excellent explanation. Thank you sir.