2004 CEMC Gauss (Grade 7) Problems/Problem 2

Problem

The value of $\frac{1}{2} - \frac{1}{8}$ is

$\textbf{(A)}\ \frac{3}{8} \qquad\textbf{(B)}\ -\frac{1}{6} \qquad\textbf{(C)}\ \frac{5}{8} \qquad\textbf{(D)}\ \frac{1}{16} \qquad\textbf{(E)}\ \frac{1}{4}$

Solution 1

We can use a common denominator in this case.

$2 = 2$ and $8 = 2^{3}$ , so we can see that the common denominator will be $8$ .

$\frac{1}{2} = \frac{1 \times 4}{2 \times 4} = \frac{4}{8}$

$\frac{1}{8} = \frac{1 \times 1}{8 \times 1} = \frac{1}{8}$

We then see:

$\frac{1}{2} - \frac{1}{8} = \frac{4}{8} - \frac{1}{8} = \frac{4 - 1}{8}$

$=\boxed {\textbf {(A) } \frac{3}{8}}$

~anabel.disher

2004 CEMC Gauss (Grade 7) (Problems • Answer Key • Resources)
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CEMC Gauss (Grade 7)

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2004 CEMC Gauss (Grade 7) Problems/Problem 2

Problem

Solution 1