8643 ÷ 9 = 960 R3
Let's divide 8643 by 9.

Step 1:
9 goes into 8 0 times with a remainder of 8.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 8 to get 8.
Bring next digit (6) of the dividend behind the 8 and repeat the process: 86 / 9

Step 2:
9 goes into 86 9 times with a remainder of 5.
Write down 9 as next digit of of the result. 
Result so far: 9
Subtract 81 from 86 to get 5.
Bring next digit (4) of the dividend behind the 5 and repeat the process: 54 / 9

Step 3:
9 goes into 54 6 times with a remainder of 0.
Write down 6 as next digit of of the result. 
Result so far: 96
Subtract 54 from 54 to get 0.
Bring next digit (3) of the dividend behind the 0 and repeat the process: 3 / 9

Step 4:
9 goes into 3 0 times with a remainder of 3.
Write down 0 as next digit of of the result. 
Result so far: 960
Subtract 0 from 3 to get 3.

The final result is 960 with a remainder of 3.