8578 ÷ 7 = 1225 R3
We're going to perform division on 8578 with 7 as the divisor.

Step 1:
7 goes into 8 1 times with a remainder of 1.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 7 from 8 to get 1.
Bring next digit (5) of the dividend behind the 1 and repeat the process: 15 / 7

Step 2:
7 goes into 15 2 times with a remainder of 1.
Write down 2 as next digit of of the result. 
Result so far: 12
Subtract 14 from 15 to get 1.
Bring next digit (7) of the dividend behind the 1 and repeat the process: 17 / 7

Step 3:
7 goes into 17 2 times with a remainder of 3.
Write down 2 as next digit of of the result. 
Result so far: 122
Subtract 14 from 17 to get 3.
Bring next digit (8) of the dividend behind the 3 and repeat the process: 38 / 7

Step 4:
7 goes into 38 5 times with a remainder of 3.
Write down 5 as next digit of of the result. 
Result so far: 1225
Subtract 35 from 38 to get 3.

The final result is 1225 with a remainder of 3.