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?
Wouldn't the fact that 1667 is close to 10,000/6 make for an easier method? I haven't worked out the details, but it might be more straightforward than the division by 3 method, at least for the first few digits.
Posted by Charlie
on 2003-10-05 14:36:43