What are the number of digits in 1! + 2! + 3!.......+100! ?

no. of digits in 1!=1

no.of digits in 2!=2..........

no. of digits in  100!=100.

So what we need to find is the sum of series-1,2,3,4.......100

we can use the formula n(n+1)/2

=>100*101/2

=>5050