80400 ÷ 7 = 11485 R5
No problem, we've got 80400 and 7 for the division.

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 (0) of the dividend behind the 1 and repeat the process: 10 / 7

Step 2:
7 goes into 10 1 times with a remainder of 3.
Write down 1 as next digit of of the result. 
Result so far: 11
Subtract 7 from 10 to get 3.
Bring next digit (4) of the dividend behind the 3 and repeat the process: 34 / 7

Step 3:
7 goes into 34 4 times with a remainder of 6.
Write down 4 as next digit of of the result. 
Result so far: 114
Subtract 28 from 34 to get 6.
Bring next digit (0) of the dividend behind the 6 and repeat the process: 60 / 7

Step 4:
7 goes into 60 8 times with a remainder of 4.
Write down 8 as next digit of of the result. 
Result so far: 1148
Subtract 56 from 60 to get 4.
Bring next digit (0) of the dividend behind the 4 and repeat the process: 40 / 7

Step 5:
7 goes into 40 5 times with a remainder of 5.
Write down 5 as next digit of of the result. 
Result so far: 11485
Subtract 35 from 40 to get 5.

The final result is 11485 with a remainder of 5.