870 ÷ 6 = 145 R0
Alright, let's work through the division of 870 by 6 step by step.

Step 1:
6 goes into 8 1 times with a remainder of 2.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 6 from 8 to get 2.
Bring next digit (7) of the dividend behind the 2 and repeat the process: 27 / 6

Step 2:
6 goes into 27 4 times with a remainder of 3.
Write down 4 as next digit of of the result. 
Result so far: 14
Subtract 24 from 27 to get 3.
Bring next digit (0) of the dividend behind the 3 and repeat the process: 30 / 6

Step 3:
6 goes into 30 5 times with a remainder of 0.
Write down 5 as next digit of of the result. 
Result so far: 145
Subtract 30 from 30 to get 0.

The final result is 145 with a remainder of 0.