Mars ([info]pili_uhane_hoku) wrote,
  • Mood: bouncy

MATH TRICK TIME!!!!!

**Multiply Up to 20X20 In Your Head**

In just FIVE minutes you should learn to quickly multiply up to 20x20 in your head. With this trick, you will be able to multiply any two numbers from 11 to 19 in your head quickly, without the use of a calculator.

I will assume that you know your multiplication table reasonably well up to 10x10.

Try this: Take 15 x 13 for an example

1. Always place the larger number of the two on top in your mind.
2. Then draw the shape of Africa mentally so it covers the 15 and the 3 from the 13 below. Those covered numbers are all you need.
3. First add 15 + 3 = 18
4. Add a zero behind it (multiply by 10) to get 180.
5. Multiply the covered lower 3 x the single digit above it the "5" (3x5= 15)
6. Add 180 + 15 = 195.

That is It! Wasn't that easy? Practice it on paper first!

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  • 7 comments

[info]defiant822

November 28 2005, 17:55:10 UTC 6 years ago

Gee...I did not know you like math. Maybe we should sit in a bar and talk about math someday. :)

[info]pili_uhane_hoku

November 29 2005, 19:06:39 UTC 6 years ago

Ohhh!

That's why you contacted me last night on AIM. I was like totally lost!?! Thanks a lot, eh. I do like math but sometimes I forget since I don't quite do math everyday.

[info]defiant822

November 29 2005, 21:05:01 UTC 6 years ago

Re: Ohhh!

Now, I have a nickname for you...blackhole.

[info]whynatty

November 30 2005, 16:10:56 UTC 6 years ago

ugh gimme a break with mathematic! *winks*

[info]pili_uhane_hoku

December 5 2005, 02:04:34 UTC 6 years ago

Haha, who said you gotta do this??!! I was bored that day so sue me....

[info]stefrose

December 5 2005, 01:46:49 UTC 6 years ago

ugghh.. the tough part would be remembering the sequences of order :-p heh xoxo

[info]pili_uhane_hoku

December 5 2005, 02:05:22 UTC 6 years ago

Yup - quite understandable - we would only remember it one day then the next day, we will move on... Forgetting what exactly we should remember in an order... Dat's life that we gotta live!
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