Question

The ten's digit in $1!+4!+7!+10!+12!+$ $13!+15!+16!+17!$ is divisible by

• A. 4
• B. 3 !
• C. 5
• D. 7

Answer 1

Answer: (B)

As we know, the last two digits of 10 ! and above factorials will be zero-zero.
$\therefore 1!+4!+7!+10!+12!+13!+15!+16!+17!$
$=1+24+5040+10!+12!+13!+15!+16!+17!$
$=5065+10!+12!+13!+15!+16!+17!$
In this series, the digit in the ten's place is 6 which is divisible by $3!$.