21215 ÷ 8 = 2651 R7
We're going to perform division on 21215 with 8 as the divisor.

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 (2) of the dividend behind the 5 and repeat the process: 52 / 8

Step 3:
8 goes into 52 6 times with a remainder of 4.
Write down 6 as next digit of of the result. 
Result so far: 26
Subtract 48 from 52 to get 4.
Bring next digit (1) of the dividend behind the 4 and repeat the process: 41 / 8

Step 4:
8 goes into 41 5 times with a remainder of 1.
Write down 5 as next digit of of the result. 
Result so far: 265
Subtract 40 from 41 to get 1.
Bring next digit (5) of the dividend behind the 1 and repeat the process: 15 / 8

Step 5:
8 goes into 15 1 times with a remainder of 7.
Write down 1 as next digit of of the result. 
Result so far: 2651
Subtract 8 from 15 to get 7.

The final result is 2651 with a remainder of 7.