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 another path? by Charlie)

I was thinking along the same lines as Charlie. All you would need to do this way is to figure out what the number is when divided by 6, and what the remainder is.

To do this, take the number divided by 6. These are the first two digits. The next is the decimal equivelant of the remainder, plus twice the first two digits, plus one.

For example, 263/6 = 43 with a remainder of 5. So 263 times 1667 is 438,421 because that equals 43 followed by the decimal representation of 5/6 or 8333 plus 2x43 plus 1.

Although this may sound harder, it would be easier to do for me.

Posted by Gamer on 2003-10-05 14:57:13