What is the units digit of (3^10)(4^13)?
Pick.
A) 2 B) 4 C) 6 D) 7 E) 8
-&gt; The ones place of (~3)^n repeats after 4 times like 39713.   The ones place of (~4)^n repeats after 2 times like 464.   Then, 3^10=3^4*2+23^2.,   4^13=4^2*6+1=4^1=~4   which is (3^10)(4^13) (3^2)(~4)=(~9)(~4)=~6. Therefore, the answer is 6.
<result>C</result>
What is the units digit of (3^10)(4^13)?