We divide 437578 by 21
We want to figure out the number of times 437578 can be divided by 21.

Moving on to step 1:
21 goes into 4 0 times with a remainder of 4.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 4, we get 4.
Take the next digit (3) from the dividend and append it to 4, then repeat: 43 / 21

On to step 2:
21 goes into 43 2 times with a remainder of 1.
Write down 2 as next digit of the result. 
Result so far: 2.0
Deduct 42 from 43 and we're left with 1.
Include the next digit (7) from the dividend after 1, then repeat: 17 / 21

Advancing to step 3:
17 divided by 21 is 0 with a remainder of 17.
Write down 0 as next digit of the result. 
Result so far: 20.0
If we subtract 0 from 17, we get 17.
Grab the next digit (5) from the dividend, add it to 17, then carry on: 175 / 21

Going ahead to step 4:
When dividing 175 by 21, we get 8 with a remainder of 7.
Put 8 as the next digit of the answer. 
Result so far: 208.0
Subtract 168 from 175 to get 7.
Fetch the next digit (7) from the dividend, attach it to 7 and continue: 77 / 21

Moving on to step 5:
When dividing 77 by 21, we get 3 with a remainder of 14.
The number 3 becomes the next digit in our result. 
Result so far: 2083.0
If we take 63 away from 77, we end up with 14.
Take the next digit (8) from the dividend and append it to 14, then repeat: 148 / 21

Moving on to step 6:
If we divide 148 by 21, we get 7 and a remainder of 1.
Write down 7 as next digit of the result. 
Result so far: 20837.0
Subtracting 147 from 148 leaves us 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.

On to step 7:
21 can be fit into 10 0 times, resulting in a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 20837.0
If we subtract 0 from 10, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Moving on to step 8:
The number 21 fits into 100 4 times, leaving a remainder of 16.
The number 4 becomes the next digit in our result. 
Result so far: 20837.04
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.

On to step 9:
The number 21 fits into 160 7 times, leaving a remainder of 13.
Record the quotient 7 as the next digit in the result. 
Result so far: 20837.047
If we subtract 147 from 160, we get 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Moving on to step 10:
21 can be fit into 130 6 times, resulting in a remainder of 4.
Use 6 as the next digit of our solution. 
Result so far: 20837.0476
If we take 126 away from 130, we end up with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Let's proceed to step 11:
40 divided by 21 is 1 with a remainder of 19.
Write down 1 as next digit of the result. 
Result so far: 20837.04761
Deduct 21 from 40 and we're left 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.

Going ahead to step 12:
When dividing 190 by 21, we get 9 with a remainder of 1.
Put 9 as the next digit of the answer. 
Result so far: 20837.047619
Subtract 189 from 190 to get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 13:
When dividing 10 by 21, we get 0 with a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 20837.047619
Deduct 0 from 10 and we're left 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.

Step 14:
21 can be fit into 100 4 times, resulting in a remainder of 16.
The next digit of our result is 4. 
Result so far: 20837.04761904
Subtracting 84 from 100 leaves us with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

After the division, we end up with 20837.04761904 and a remainder of 1.6e-08.