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?

(In reply to solution by RoyCook)

i think when the author gives the number in the form nnn, she still includes 3 dissimilar digits abc such as 101 which is not divisible by 3. (?)

Posted by mohan on 2003-10-06 01:42:22