99 ÷ 3 = 33 R0
Let's divide 99 by 3.

Step 1:
3 goes into 9 3 times with a remainder of 0.
Write down 3 as next digit of of the result. 
Result so far: 3
Subtract 9 from 9 to get 0.
Bring next digit (9) of the dividend behind the 0 and repeat the process: 9 / 3

Step 2:
3 goes into 9 3 times with a remainder of 0.
Write down 3 as next digit of of the result. 
Result so far: 33
Subtract 9 from 9 to get 0.

The final result is 33 with a remainder of 0.