51409 ÷ 2 = 25704 R1
Let's divide 51409 by 2.

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

Step 2:
2 goes into 11 5 times with a remainder of 1.
Write down 5 as next digit of of the result. 
Result so far: 25
Subtract 10 from 11 to get 1.
Bring next digit (4) of the dividend behind the 1 and repeat the process: 14 / 2

Step 3:
2 goes into 14 7 times with a remainder of 0.
Write down 7 as next digit of of the result. 
Result so far: 257
Subtract 14 from 14 to get 0.
Bring next digit (0) of the dividend behind the 0 and repeat the process: 0 / 2

Step 4:
2 goes into 0 0 times with a remainder of 0.
Write down 0 as next digit of of the result. 
Result so far: 2570
Subtract 0 from 0 to get 0.
Bring next digit (9) of the dividend behind the 0 and repeat the process: 9 / 2

Step 5:
2 goes into 9 4 times with a remainder of 1.
Write down 4 as next digit of of the result. 
Result so far: 25704
Subtract 8 from 9 to get 1.

The final result is 25704 with a remainder of 1.