81 ÷ 5 = 16 R1
We're going to perform division on 81 with 5 as the divisor.

Step 1:
5 goes into 8 1 times with a remainder of 3.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 5 from 8 to get 3.
Bring next digit (1) of the dividend behind the 3 and repeat the process: 31 / 5

Step 2:
5 goes into 31 6 times with a remainder of 1.
Write down 6 as next digit of of the result. 
Result so far: 16
Subtract 30 from 31 to get 1.

The final result is 16 with a remainder of 1.