90243 ÷ 8 = 11280 R3
Alright, let's work through the division of 90243 by 8 step by step.

Step 1:
8 goes into 9 1 times with a remainder of 1.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 8 from 9 to get 1.
Bring next digit (0) of the dividend behind the 1 and repeat the process: 10 / 8

Step 2:
8 goes into 10 1 times with a remainder of 2.
Write down 1 as next digit of of the result. 
Result so far: 11
Subtract 8 from 10 to get 2.
Bring next digit (2) of the dividend behind the 2 and repeat the process: 22 / 8

Step 3:
8 goes into 22 2 times with a remainder of 6.
Write down 2 as next digit of of the result. 
Result so far: 112
Subtract 16 from 22 to get 6.
Bring next digit (4) of the dividend behind the 6 and repeat the process: 64 / 8

Step 4:
8 goes into 64 8 times with a remainder of 0.
Write down 8 as next digit of of the result. 
Result so far: 1128
Subtract 64 from 64 to get 0.
Bring next digit (3) of the dividend behind the 0 and repeat the process: 3 / 8

Step 5:
8 goes into 3 0 times with a remainder of 3.
Write down 0 as next digit of of the result. 
Result so far: 11280
Subtract 0 from 3 to get 3.

The final result is 11280 with a remainder of 3.