21111 ÷ 3 = 7037 R0
We're going to perform division on 21111 with 3 as the divisor.

Step 1:
3 goes into 2 0 times with a remainder of 2.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 2 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 3

Step 2:
3 goes into 21 7 times with a remainder of 0.
Write down 7 as next digit of of the result. 
Result so far: 7
Subtract 21 from 21 to get 0.
Bring next digit (1) of the dividend behind the 0 and repeat the process: 1 / 3

Step 3:
3 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of of the result. 
Result so far: 70
Subtract 0 from 1 to get 1.
Bring next digit (1) of the dividend behind the 1 and repeat the process: 11 / 3

Step 4:
3 goes into 11 3 times with a remainder of 2.
Write down 3 as next digit of of the result. 
Result so far: 703
Subtract 9 from 11 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 3

Step 5:
3 goes into 21 7 times with a remainder of 0.
Write down 7 as next digit of of the result. 
Result so far: 7037
Subtract 21 from 21 to get 0.

The final result is 7037 with a remainder of 0.