99643 ÷ 8 = 12455 R3
No problem, we've got 99643 and 8 for the division.

Step 1:
8 goes into 9 1 times with a remainder of 1.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 8 from 9 to get 1.
Bring next digit (9) of the dividend behind the 1 and repeat the process: 19 / 8

Step 2:
8 goes into 19 2 times with a remainder of 3.
Write down 2 as next digit of of the result. 
Result so far: 12
Subtract 16 from 19 to get 3.
Bring next digit (6) of the dividend behind the 3 and repeat the process: 36 / 8

Step 3:
8 goes into 36 4 times with a remainder of 4.
Write down 4 as next digit of of the result. 
Result so far: 124
Subtract 32 from 36 to get 4.
Bring next digit (4) of the dividend behind the 4 and repeat the process: 44 / 8

Step 4:
8 goes into 44 5 times with a remainder of 4.
Write down 5 as next digit of of the result. 
Result so far: 1245
Subtract 40 from 44 to get 4.
Bring next digit (3) of the dividend behind the 4 and repeat the process: 43 / 8

Step 5:
8 goes into 43 5 times with a remainder of 3.
Write down 5 as next digit of of the result. 
Result so far: 12455
Subtract 40 from 43 to get 3.

The final result is 12455 with a remainder of 3.