81911 ÷ 2 = 40955 R1
Let's divide 81911 by 2.

Step 1:
2 goes into 8 4 times with a remainder of 0.
Write down 4 as next digit of of the result. 
Result so far: 4
Subtract 8 from 8 to get 0.
Bring next digit (1) of the dividend behind the 0 and repeat the process: 1 / 2

Step 2:
2 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of of the result. 
Result so far: 40
Subtract 0 from 1 to get 1.
Bring next digit (9) of the dividend behind the 1 and repeat the process: 19 / 2

Step 3:
2 goes into 19 9 times with a remainder of 1.
Write down 9 as next digit of of the result. 
Result so far: 409
Subtract 18 from 19 to get 1.
Bring next digit (1) of the dividend behind the 1 and repeat the process: 11 / 2

Step 4:
2 goes into 11 5 times with a remainder of 1.
Write down 5 as next digit of of the result. 
Result so far: 4095
Subtract 10 from 11 to get 1.
Bring next digit (1) of the dividend behind the 1 and repeat the process: 11 / 2

Step 5:
2 goes into 11 5 times with a remainder of 1.
Write down 5 as next digit of of the result. 
Result so far: 40955
Subtract 10 from 11 to get 1.

The final result is 40955 with a remainder of 1.