6123 ÷ 8 = 765 R3
No problem, we've got 6123 and 8 for the division.

Step 1:
8 goes into 6 0 times with a remainder of 6.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 6 to get 6.
Bring next digit (1) of the dividend behind the 6 and repeat the process: 61 / 8

Step 2:
8 goes into 61 7 times with a remainder of 5.
Write down 7 as next digit of of the result. 
Result so far: 7
Subtract 56 from 61 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: 76
Subtract 48 from 52 to get 4.
Bring next digit (3) of the dividend behind the 4 and repeat the process: 43 / 8

Step 4:
8 goes into 43 5 times with a remainder of 3.
Write down 5 as next digit of of the result. 
Result so far: 765
Subtract 40 from 43 to get 3.

The final result is 765 with a remainder of 3.