138 ÷ 6 = 23 R0
No problem, we've got 138 and 6 for the division.

Step 1:
6 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 1 to get 1.
Bring next digit (3) of the dividend behind the 1 and repeat the process: 13 / 6

Step 2:
6 goes into 13 2 times with a remainder of 1.
Write down 2 as next digit of of the result. 
Result so far: 2
Subtract 12 from 13 to get 1.
Bring next digit (8) of the dividend behind the 1 and repeat the process: 18 / 6

Step 3:
6 goes into 18 3 times with a remainder of 0.
Write down 3 as next digit of of the result. 
Result so far: 23
Subtract 18 from 18 to get 0.

The final result is 23 with a remainder of 0.