Find the smallest multiple of 9 with no odd digits.

Use your head ONLY.

In order to be a multiple of 9, the sum of the digits must be a multiple of 9. If all the digits are even, then it must be an even multiple of 9, the smallest of which is 18. Two digits won't do it, as the smallest (or rather only) 2 digits adding to 18 are 99, both digits being odd. The smallest such 3-digit number is 288, with as much of the load as possible placed toward the lower order digits.

Posted by Charlie on 2012-07-31 22:47:54