2025 AMC 8 Problems/Problem 6
Problem
Sekou writes the numbers After he erases one of his numbers, the sum of the remaining four numbers is a multiple of Which number did he erase?
A)15 B)16 C)17 D)18 E)19
Solution 1
First, we sum the numbers to get . The number subtracted therefore must be 1 more than a multiple of 4. Thus, the answer is . ~Gavin_Deng
Solution 2
We consider modulo . The sum of the residues of these numbers modulo is . Hence, the number being subtracted must be congruent to modulo . The only such number here is . ~cxsmi
Solution 3
, subtracting the first option gives , the largest mutliple of 4 less or equal to is , . ~ alwaysgonnagiveyouup