91573934 ÷ 21 
We want to divide 91573934 by 21.

Going ahead to step 1:
21 goes into 9 0 times with a remainder of 9.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 9 leaves us with 9.
Take the next digit (1) from the dividend and append it to 9, then repeat: 91 / 21

On to step 2:
21 can be fit into 91 4 times, resulting in a remainder of 7.
Write down 4 as next digit of the result. 
Result so far: 4.0
The remainder is 7 after subtracting 84 from 91.
Append the next digit (5) from the dividend to 7 and continue with: 75 / 21

Going ahead to step 3:
75 divided by 21 is 3 with a remainder of 12.
Write down 3 as next digit of the result. 
Result so far: 43.0
If we subtract 63 from 75, we get 12.
Append the next digit (7) from the dividend to 12 and continue with: 127 / 21

Moving on to step 4:
When dividing 127 by 21, we get 6 with a remainder of 1.
The number 6 becomes the next digit in our result. 
Result so far: 436.0
Subtract 126 from 127 to get 1.
Include the next digit (3) from the dividend after 1, then repeat: 13 / 21

Advancing to step 5:
13 divided by 21 is 0 with a remainder of 13.
Use 0 as the next digit of our solution. 
Result so far: 4360.0
If we take 0 away from 13, we end up with 13.
Fetch the next digit (9) from the dividend, attach it to 13 and continue: 139 / 21

Advancing to step 6:
The number 21 fits into 139 6 times, leaving a remainder of 13.
Write down 6 as next digit of the result. 
Result so far: 43606.0
Subtracting 126 from 139 leaves us with 13.
Append the next digit (3) from the dividend to 13 and continue with: 133 / 21

Step 7:
If we divide 133 by 21, we get 6 and a remainder of 7.
Put 6 as the next digit of the answer. 
Result so far: 436066.0
The remainder is 7 after subtracting 126 from 133.
Append the next digit (4) from the dividend to 7 and continue with: 74 / 21

On to step 8:
74 divided by 21 is 3 with a remainder of 11.
Record the quotient 3 as the next digit in the result. 
Result so far: 4360663.0
Subtract 63 from 74 to get 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

On to step 9:
21 goes into 110 5 times with a remainder of 5.
Write down 5 as next digit of the result. 
Result so far: 4360663.5
The remainder is 5 after subtracting 105 from 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Going ahead to step 10:
21 can be fit into 50 2 times, resulting in a remainder of 8.
The next digit of our result is 2. 
Result so far: 4360663.52
Subtracting 42 from 50 leaves us with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Advancing to step 11:
21 can be fit into 80 3 times, resulting in a remainder of 17.
Record the quotient 3 as the next digit in the result. 
Result so far: 4360663.523
Subtracting 63 from 80 leaves us with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Let's proceed to step 12:
When dividing 170 by 21, we get 8 with a remainder of 2.
Record the quotient 8 as the next digit in the result. 
Result so far: 4360663.5238
Deduct 168 from 170 and we're left with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Advancing to step 13:
21 goes into 20 0 times with a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 4360663.5238
Subtracting 0 from 20 leaves us with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Step 14:
21 can be fit into 200 9 times, resulting in a remainder of 11.
The number 9 becomes the next digit in our result. 
Result so far: 4360663.523809
The remainder is 11 after subtracting 189 from 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

On to step 15:
21 goes into 110 5 times with a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 4360663.5238095
If we subtract 105 from 110, we get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

On to step 16:
When dividing 50 by 21, we get 2 with a remainder of 8.
Use 2 as the next digit of our solution. 
Result so far: 4360663.52380952
If we take 42 away from 50, we end up with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

After the division, we end up with 4360663.52380952 and a remainder of 8e-09.