42 ÷ 8 = 5 R2
We're going to perform division on 42 with 8 as the divisor.

Step 1:
8 goes into 4 0 times with a remainder of 4.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 4 to get 4.
Bring next digit (2) of the dividend behind the 4 and repeat the process: 42 / 8

Step 2:
8 goes into 42 5 times with a remainder of 2.
Write down 5 as next digit of of the result. 
Result so far: 5
Subtract 40 from 42 to get 2.

The final result is 5 with a remainder of 2.