21651 ÷ 8 = 2706 R3
Let's divide 21651 by 8.

Step 1:
8 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 / 8

Step 2:
8 goes into 21 2 times with a remainder of 5.
Write down 2 as next digit of of the result. 
Result so far: 2
Subtract 16 from 21 to get 5.
Bring next digit (6) of the dividend behind the 5 and repeat the process: 56 / 8

Step 3:
8 goes into 56 7 times with a remainder of 0.
Write down 7 as next digit of of the result. 
Result so far: 27
Subtract 56 from 56 to get 0.
Bring next digit (5) of the dividend behind the 0 and repeat the process: 5 / 8

Step 4:
8 goes into 5 0 times with a remainder of 5.
Write down 0 as next digit of of the result. 
Result so far: 270
Subtract 0 from 5 to get 5.
Bring next digit (1) of the dividend behind the 5 and repeat the process: 51 / 8

Step 5:
8 goes into 51 6 times with a remainder of 3.
Write down 6 as next digit of of the result. 
Result so far: 2706
Subtract 48 from 51 to get 3.

The final result is 2706 with a remainder of 3.