Question

Let s be the sum of all digits used in writing all numbers from 1 to 1010.find s

Answer 1

We know, s = n/2 [a + l ]
Here, n = 1010
a = 1
l = 1010

Substitute their values, 
s = 1010/2 [1 + 1010]
s = 505 [ 1011]
s = 510555

In short, Your Answer would be 5,10,555

Hope this helps!