[hl0m4n]

http://www.newsobserver.com/news/hea...y/1641012.html



been seeing alot of these ads on the tv, about being able to do any math problem in your head from multiplying to division, etc but is there really a code in math, if cracked gives you einstein like powers ?

[radix]

Originally Posted by hl0m4n

http://www.newsobserver.com/news/hea...y/1641012.html



been seeing alot of these ads on the tv, about being able to do any math problem in your head from multiplying to division, etc but is there really a code in math, if cracked gives you einstein like powers ?

There are tons of tricks to increase your speed with mental arithmetic. There is no overall "code" however. This is just another trick. The best thing most people can do to do most arithmetic is to stop working with the least significant digits first, and do operations from left to right. There are myriad other heuristics for speeding things up, including rules with nines, fives, etc. Here's a classic one for finding the cube root of any number up to one million in your head.

% bc -l
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'. 
53 * 53 * 53
148877

From memory:

1^3 = 1
2^3 = 8
3^3 = 27
4^3 = 64
5^3 = 125
6^3 = 216
7^3 = 343
8^3 = 512
9^3 = 729

take number the 148877, split it into groups of three from the right:

877 - the only cube 1-9 that ends in seven is 3, so the last number is 3.

148 - the largest cube 1-9 that fits into 148 is 125. 125 is the cube of 5. So the first number is 5.

5 3 = 53

There are tons of tricks like this in the math world.

[darkphantom]

there is a "method" of multiplying any two multidigit numbers in your head...they teach in MCAT class and other places as well...just google it

[radix]

Oh yeah, about multiplication specifically... There are several different ways of multiplying numbers. One interesting one was discovered by John Napier and is known as "Napier's bones". If you google that I bet you'll probably find tons of other methods. Although for some reason I can't find it on my bookshelf, this book has several different methods in it:

http://www.amazon.com/Story-Numbers-...ref=pd_sim_b_2

I can't seem to find my copy, but that is the book I first read about how the Egyptians multiplied numbers and Napier's bones.