251 ÷ 9 = 27 R8
We're going to perform division on 251 with 9 as the divisor.

Step 1:
9 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 (5) of the dividend behind the 2 and repeat the process: 25 / 9

Step 2:
9 goes into 25 2 times with a remainder of 7.
Write down 2 as next digit of of the result. 
Result so far: 2
Subtract 18 from 25 to get 7.
Bring next digit (1) of the dividend behind the 7 and repeat the process: 71 / 9

Step 3:
9 goes into 71 7 times with a remainder of 8.
Write down 7 as next digit of of the result. 
Result so far: 27
Subtract 63 from 71 to get 8.

The final result is 27 with a remainder of 8.