5 cool math tricks ft. Technicality

Math can be fun when you play with the rules, use it to do everyday things like fast math for calculating tips, and do some math magic tricks! Plus, math is the language of physics. Check out these 5 fun math tricks with Alex from Technicality.

Creator: Dianna Cowern
Editor: Jabril Ashe/Dianna Cowern
Writer: Sophia Chen
Animations: Kyle Norby

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Music: APM

[tibees]

Good video to get people interested in math, but there are lots of cool math ideas that deal with more than just arithmetic

[physicsgirl]

Just clarifying at 2:58 (because I know it is sometimes hard to catch all the audio and visuals at the same time) that 5 x 8 is indeed 44 in base 9!

[noahm]

When I multiply with 9 I operate like this
n*9=(n*10)-n
That was the first thing I did when I saw this at school

[grzegorzcichosz]

Am I alone in the feeling that this trick with multiplying with hands makes multiplying harder?

[Ccb]

Teacher: "Alright class, today we're doing square roots"
Me: *pulls out a pile of pipe cleaners* "Alright, I'm ready"

[JohnMichaelStrubhart]

The best thing about tricks like this is that they help you _understand_ the math behind them - particularly elements of number theory. This is a skill far more valuable than memorizing multiplication and division tables.

[Sela]

This channel is so amazing! Making science and math fun and entertaining, let alone understandable for people isn't easy. Nothing but love, admiration and appreciation!

[alkotreshnik]

How did you measure 7.96875 with the ruler eagle eye?

[levishu]

That 9 times table thing with the fingers is really inefficient. Just multiply the number by 10 and subtract the original number.

[zach]

I figured out a fun way to multiply by 8s on your fingers. Using one hand, you count, via the fingers, the number you want to multiply 8 by, then double the number of fingers+thumb to the right of the lowered finger. For example, 8x2 would look like [I-IIi]. This shows [10+(3x2)]=16 Doubling the fingers+thumb on the right gives a result of 16.

(I = an up finger, - = a down finger, i = a thumb, and [ ] are used to distinguish between the two hands.)

For multiplying past 6, cycle the down finger back around to the start and use the fingers on your other hand as placeholders, each equal to 40.

So, 8x9 would end up showing the following: [III-i][i----], which is [30+(1x2)]+[40]=72.
And, 8x22 would end with: [I-IIi][iIII-], which is [10+(3x2)]+[40+40+40+40]=176.

I'm happy bc I just came up with this on my own! Plus, it allows you to multiply by 8s up to 30.

[ggiiuulliio]

well "this is episode n", you already made my day :D hahaha

[jamescarmody]

I LOVE math videos! Please, Diana, make some more of these!

[joshhickman]

Pattern at 3:07 is because:
"tens" digit is because in base n, (n-1) * j where j < n will be n * j - j -- and therefore always have a "tens" digit of j-1. The twos are there because -1 * -2 mod n = 2.

[adnamamedia]

I would love more of these! I absolutely love little tricks like this!

[jeopardy]

1 cool english trick: put an S on the end of math

[Jabrils]

Stopping by to say great video Dianna! Keep up the great work! :D

[sidhollander]

Why/how did you select 715, 364 and 924 to multiply, respectively, the remainders 1, 3 and 5?

[jquick]

I love these kinds of tricks that help you understand the a&p of numbers a little better! Thanks!

[johnclarke]

Your demonstration for multiplying by eleven reminded me of a book my father brought home in the 60's. In the foreword it told of a small girl multiplying 735352314 by 11 who calculated the answer 8088875454 in less than a minute. A boy in the same class multiplied 5132437201 by 452736502785 to get the answer 2323641669144374104785 in seventy seconds. Both were students of the Trachtenberg system. The first thing I learned was to multiply by eleven and it uses the same concept of adding one digit of the number to the previous digit carrying when necessary. Very helpful in those days when a four function electronic calculator cost $400 and could only display 8 digits. BTW, the book is available online in PDF for those who are curious.

[Kaneanite]

This video only serves to remind me that I fail at math.