1998 CEMC Gauss (Grade 7) Problems/Problem 2

Problem

The number $4567$ is tripled. The ones digit (units digit) in the resulting number is

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

Solution 1

Multiply: $4567 \cdot 3 = 13701.$ The units digit is the rightmost digit, which is 1.

The answer is $\boxed{E}.$

-edited by coolmath34

Solution 2

The units digit of a product only depends on the units digits of the numbers being multiplied, which reduces the problem down to $7 \cdot 3 = 21$ , meaning that the units digit is 1 and the answer is $\boxed{E}$ .

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1998 CEMC Gauss (Grade 7) Problems/Problem 2

Problem

Solution 1

Solution 2