591721 ÷ 21 
We want to divide 591721 by 21.

Going ahead to step 1:
21 goes into 5 0 times with a remainder of 5.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 5, we get 5.
Include the next digit (9) from the dividend after 5, then repeat: 59 / 21

On to step 2:
59 divided by 21 is 2 with a remainder of 17.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
If we subtract 42 from 59, we get 17.
Include the next digit (1) from the dividend after 17, then repeat: 171 / 21

Moving on to step 3:
The number 21 fits into 171 8 times, leaving a remainder of 3.
Record the quotient 8 as the next digit in the result. 
Result so far: 28.0
The remainder is 3 after subtracting 168 from 171.
Grab the next digit (7) from the dividend, add it to 3, then carry on: 37 / 21

Step 4:
21 goes into 37 1 times with a remainder of 16.
The next digit of our result is 1. 
Result so far: 281.0
The remainder is 16 after subtracting 21 from 37.
Bring next digit (2) of the dividend behind the 16 and repeat the process: 162 / 21

Step 5:
21 can be fit into 162 7 times, resulting in a remainder of 15.
The number 7 becomes the next digit in our result. 
Result so far: 2817.0
Subtracting 147 from 162 leaves us with 15.
Bring next digit (1) of the dividend behind the 15 and repeat the process: 151 / 21

Let's proceed to step 6:
21 can be fit into 151 7 times, resulting in a remainder of 4.
Use 7 as the next digit of our solution. 
Result so far: 28177.0
If we subtract 147 from 151, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

On to step 7:
40 divided by 21 is 1 with a remainder of 19.
The number 1 becomes the next digit in our result. 
Result so far: 28177.1
If we subtract 21 from 40, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Let's proceed to step 8:
21 goes into 190 9 times with a remainder of 1.
Write down 9 as next digit of the result. 
Result so far: 28177.19
Deduct 189 from 190 and we're left with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Advancing to step 9:
21 can be fit into 10 0 times, resulting in a remainder of 10.
Write down 0 as next digit of the result. 
Result so far: 28177.19
If we take 0 away from 10, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

On to step 10:
When dividing 100 by 21, we get 4 with a remainder of 16.
Record the quotient 4 as the next digit in the result. 
Result so far: 28177.1904
If we subtract 84 from 100, we get 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Let's proceed to step 11:
160 divided by 21 is 7 with a remainder of 13.
The next digit of our result is 7. 
Result so far: 28177.19047
Deduct 147 from 160 and we're left with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Let's proceed to step 12:
21 can be fit into 130 6 times, resulting in a remainder of 4.
The number 6 becomes the next digit in our result. 
Result so far: 28177.190476
The remainder is 4 after subtracting 126 from 130.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

On to step 13:
21 goes into 40 1 times with a remainder of 19.
Write down 1 as next digit of the result. 
Result so far: 28177.1904761
If we take 21 away from 40, we end up with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Moving on to step 14:
The number 21 fits into 190 9 times, leaving a remainder of 1.
Use 9 as the next digit of our solution. 
Result so far: 28177.19047619
Deduct 189 from 190 and we're left with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

The final outcome is 28177.19047619, with a leftover of 1e-09.