Question

The units digit of the expression ${125}^{813}\times {553}^{3703}\times {4532}^{828}$ is

• A. 4
• B. 2
• C. 5

Answer 1

Any number ending with 5 raised to any power will always end in 5 as its unit's digit. For 3, we know that it follows the cyclicity of 4, so ${553}^{3703}$ is the same as finding the unit's digit of $3^3$ whose unit's digit is 7. For 2, cyclicity is 4, therefore, ${4532}^{828}$ is the same as $2^4$ which ends in 6.
Hence,
$5\times 7\times 6=0$. option (c) is correct.