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2021 Mock AMC 8 Problems/Problem 1

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Problem

What is the value of $1-2+3-4+5-6+7-8+9$?

$\mathrm{(A)}\ 4 \qquad\mathrm{(B)}\ 5 \qquad\mathrm{(C)}\ 6 \qquad\mathrm{(D)}\ 7 \qquad\mathrm{(E)}\ 25$

Solution 1

Since $1-2+3-4+5-6+7-8$ is $-4$, so we have $-4 + 9 = 5$ Therefore, our answer is $\boxed{\textbf{(B) } 5} \qquad$

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