Find the smallest three-digit integer with the property that its triple has only even digits.
, 2008
Solution
Denote the three-digit number by . Its triple is equal to
Obviously, has to be at least 1. If and we want the digit at the hundreds in to be even, we require , which implies . The least possible number that satisfies this inequality is 34. The solution is 134 and its triple is 402.
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