MathDB
Sum of the Digits of a Large Product

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March 8, 2009

Problem Statement

In their base 10 10 representation, the integer a a consists of a sequence of 1985 1985 eights and the integer b b consists of a sequence of 1985 1985 fives. What is the sum of the digits of the base 10 representation of 9ab 9ab? <spanclass=′latex−bold′>(A)</span> 15880<spanclass=′latex−bold′>(B)</span> 17856<spanclass=′latex−bold′>(C)</span> 17865<spanclass=′latex−bold′>(D)</span> 17874<spanclass=′latex−bold′>(E)</span> 19851 <span class='latex-bold'>(A)</span>\ 15880 \qquad <span class='latex-bold'>(B)</span>\ 17856 \qquad <span class='latex-bold'>(C)</span>\ 17865 \qquad <span class='latex-bold'>(D)</span>\ 17874 \qquad <span class='latex-bold'>(E)</span>\ 19851
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