The ones (units) digit of 542 is 2 . When 542 is multiplied by 3 , the ones (units) digit of the result is
(A) 9
(B) 3
(C) 5
(D) 4
(E) 6
Since $542 \times 3=1626$, the ones digit of the result is 6 .

Note that the ones digit of a product only depends on the ones digits of the numbers being multiplied, so we could in fact multiply $2 \times 3$ and look at the ones digit of this product.

ANSWER: (E)