Question

Find the unit digit of the number ${99}^{123}.$

• A. 9
• B. 1
• C. 8
• D. 3

Answer 1

The correct option is A 9

Here, unit digit of the base is 9 and exponent 123 is odd.

For odd exponent of 9 unit digit of the number will be 9 and for even exponent of 9, unit digit of the number will be 1.
Hence, unit digit of ${99}^{123}$ will be 9.