2013 CEMC Gauss (Grade 7) Problems/Problem 2

Problem 2

Which of the following numbers is a multiple of 9?

$\textbf{(A)}\ 50 \qquad\textbf{(B)}\ 40\qquad\textbf{(C)}\ 35\qquad\textbf{(D)}\ 45\qquad\textbf{(E)}\ 5$

Solution

You can find if a number is a multiple of 9 by adding the digits and seeing if it is a multiple of 9. By trial-and-error you can see that $\boxed{\textbf{(D)}\ 45}$ is the answer