Question

Consider $a^x$. For $x=10$, when $x$ divides $a$, the remainder is 4. Find the units digit of $a^x$.

• A. 6
• B. 5
• C. 3
• D. 4

Answer 1

The correct option is A 6

In a division operation, the remainder says how much is the divided greater than a multiple of the divisor.
All multiples of 10 have 0 in the units place. Remainder 4, certainly means the units digits of the base is 4.

When 4 as base raised to an even power 10, the units digit is always 6.