#1 2020-06-29 06:04:47

pi_cubed

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From: A rhombicosidodecahedron

Registered: 2020-06-22

Posts: 50

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Do mental multiplication quickly

This is more of an algorithim, but here is how you can do any number times a one digit number quickly.

167859*7
1*7
6*7
7*7
8*7
5*7
9*7
 |
\/
7
42
49
56
35
63
'''To put the numbers together just put them next to each other e.g 12*3 => 1*3 and 2*3 => 3 and 6 => 36. If the result has a 2 digit number then add the tens place from the 2 digit number to the next number left or above's ones place.'''

Credit to Abhishek V. R. for this method of doing mental multiplication.
Edit: I may not have written the part about putting the numbers together right. Please google "ofpad mental multiplication left to right" for the correct method.

Last edited by pi_cubed (2020-06-29 06:13:15)

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e to the i pi plus 1 is zero -Leonhard Euler | a squared plus b squared equals c squared -Pythagoras | Energy equals mass times the speed of light squared -Albert Einstein | i² = -1 |
X Y X' Y' ≠ X' Y' X Y = Y' X' Y X -Me talking about some random group theory relationships