79421 ÷ 4 = 19855 R1
We're going to perform division on 79421 with 4 as the divisor.

Step 1:
4 goes into 7 1 times with a remainder of 3.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 4 from 7 to get 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 4

Step 2:
4 goes into 39 9 times with a remainder of 3.
Write down 9 as next digit of of the result. 
Result so far: 19
Subtract 36 from 39 to get 3.
Bring next digit (4) of the dividend behind the 3 and repeat the process: 34 / 4

Step 3:
4 goes into 34 8 times with a remainder of 2.
Write down 8 as next digit of of the result. 
Result so far: 198
Subtract 32 from 34 to get 2.
Bring next digit (2) of the dividend behind the 2 and repeat the process: 22 / 4

Step 4:
4 goes into 22 5 times with a remainder of 2.
Write down 5 as next digit of of the result. 
Result so far: 1985
Subtract 20 from 22 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 4

Step 5:
4 goes into 21 5 times with a remainder of 1.
Write down 5 as next digit of of the result. 
Result so far: 19855
Subtract 20 from 21 to get 1.

The final result is 19855 with a remainder of 1.