MathDB
Triangular array

Source: Problem #9 2016 AMC 10A

February 3, 2016
AMCAMC 10AMC 10 A2016 AMC 10AAMC 122016 AMC 12AAMC 12A

Problem Statement

A triangular array of 20162016 coins has 11 coin in the first row, 22 coins in the second row, 33 coins in the third row, and so on up to NN coins in the NNth row. What is the sum of the digits of NN?
<spanclass=′latex−bold′>(A)</span> 6<spanclass=′latex−bold′>(B)</span> 7<spanclass=′latex−bold′>(C)</span> 8<spanclass=′latex−bold′>(D)</span> 9<spanclass=′latex−bold′>(E)</span> 10<span class='latex-bold'>(A)</span>\ 6\qquad<span class='latex-bold'>(B)</span>\ 7\qquad<span class='latex-bold'>(C)</span>\ 8\qquad<span class='latex-bold'>(D)</span>\ 9\qquad<span class='latex-bold'>(E)</span>\ 10
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