Question

The tens digit of $1!+2!+3!+\dots +49!$ is

Answer 1

Answer: 1

$1!+2!+3!+4!=33$ Also $5!=120,6!=720,7!=5040,8!=40320and9!=326880$
The tens digit of $1!+2!+3!+\dots +9!=1$
Also note that n! is divisible by 100 for $n\ge 10$ so that tens digit of $10!+11!+\dots +49!$ is zero
Therefore, tens digit of $1!+2!+3!+\dots +49!$ is 1.