2018 AMC 8 Problems/Problem 7

Problem

The $5$ -digit number $\underline{2}$ $\underline{0}$ $\underline{1}$ $\underline{8}$ $\underline{U}$ is divisible by $9$ . What is the remainder when this number is divided by $8$ ?

$\textbf{(A) }1\qquad\textbf{(B) }3\qquad\textbf{(C) }5\qquad\textbf{(D) }6\qquad\textbf{(E) }7$

Solution

We use the property that the digits of a number must sum to a multiple of $9$ if it are divisible by $9$ . This means $2+0+1+8+U$ must be divisible by $9$ . The only possible value for $U$ then must be $7$ . Since we are looking for the remainder when divided by $8$ , we can ignore the thousands. The remainder when $187$ is divided by $8$ is $\boxed{\textbf{(B) }3}$ .

20187 mod 8 =_ 3

Video Solution

https://youtu.be/6xNkyDgIhEE?t=2341

https://youtu.be/doHZiAT36BY

~savannahsolver

2018 AMC 8 (Problems • Answer Key • Resources)
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2018 AMC 8 Problems/Problem 7

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Video Solution

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