Question

Unit digit in the number $(12357{)}^{655}$ is

• A. $1$
• B. $3$
• C. $7$
• D. $9$

Answer 1

The correct option is B $3$

unit digit of $(12357{)}^{655}$

$=$ unit digit of $\left(7^{655}\right)=7^{4\times 163+3}=7^{4\times 143}+7^3$

$=$ unit digit is $(1\times 3)=$ unit digit is 3.