MathDB
2019 Individual #19

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May 1, 2022
2019 Individual

Problem Statement

Let S(n)S(n) denote the sum of digits of an integer nn (For example, S(17)=1+7=8S(17) = 1 + 7 = 8). If a positive two digit integer is randomly selected, what is the probability S(S(n))≥8S(S(n)) \ge 8?
<spanclass=′latex−bold′>(A)</span>0<spanclass=′latex−bold′>(B)</span>19<spanclass=′latex−bold′>(C)</span>29<spanclass=′latex−bold′>(D)</span>1145<spanclass=′latex−bold′>(E)</span>1345<span class='latex-bold'>(A) </span>0\qquad<span class='latex-bold'>(B) </span>\dfrac19\qquad<span class='latex-bold'>(C) </span>\dfrac29\qquad<span class='latex-bold'>(D) </span>\dfrac{11}{45}\qquad<span class='latex-bold'>(E) </span>\dfrac{13}{45}
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