Question

What is the unit digit in $({6374}^{1793}\times {625}^{317}\times {341}^{491})$?

• A. $0$
• B. $2$
• C. $3$
• D. $5$

Answer 1

The correct option is A $0$

Unit digit in ${6374}^{1993}=$ Unit digit in ${\left(4\right)}^{1793}$
=Unit digit in $[{\left(4^2\right)}^{896}\times 4]$
=Unit digit in $(6\times 4)=4$
Unit digit in ${\left(625\right)}^{317}=$ Unit digit in ${\left(5\right)}^{317}=5$
Unit digit in ${\left(341\right)}^{491}=$ Unit digit in ${\left(1\right)}^{491}=1$
Required digit$=$ Unit digit in $(4\times 5\times 1)=0$