I can multiply any three-digit number by 1667 in my head, usually in less than 10 seconds.

Also, to make it even more impressive, I come up with the digits of the result in proper order (not in reverse!)

How can I do this?

If it isn't clear in my previous post ,
If nnn is divisible by 3 then nnn/3 are the last 3 digits
Also if nnn is divisible by 6 you'll need to include the 0000's following the decimal point.
eg 768 * 1667
1. 768/3 = 256
2. 256/2 = 128.00000
result 1280 256

Posted by Lee on 2003-10-05 14:23:41