We're dividing 448173 by 21 
We want to figure out the number of times 448173 can be divided by 21.

Step 1:
21 can be fit into 4 0 times, resulting in a remainder of 4.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 4 after subtracting 0 from 4.
Bring next digit (4) of the dividend behind the 4 and repeat the process: 44 / 21

Moving on to step 2:
The number 21 fits into 44 2 times, leaving a remainder of 2.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
If we subtract 42 from 44, we get 2.
Bring next digit (8) of the dividend behind the 2 and repeat the process: 28 / 21

Advancing to step 3:
21 can be fit into 28 1 times, resulting in a remainder of 7.
The next digit of our result is 1. 
Result so far: 21.0
If we take 21 away from 28, we end up with 7.
Take the next digit (1) from the dividend and append it to 7, then repeat: 71 / 21

Step 4:
21 can be fit into 71 3 times, resulting in a remainder of 8.
The number 3 becomes the next digit in our result. 
Result so far: 213.0
If we take 63 away from 71, we end up with 8.
Grab the next digit (7) from the dividend, add it to 8, then carry on: 87 / 21

Moving on to step 5:
21 goes into 87 4 times with a remainder of 3.
The number 4 becomes the next digit in our result. 
Result so far: 2134.0
Subtract 84 from 87 to get 3.
Grab the next digit (3) from the dividend, add it to 3, then carry on: 33 / 21

Going ahead to step 6:
21 goes into 33 1 times with a remainder of 12.
Write down 1 as next digit of the result. 
Result so far: 21341.0
Subtract 21 from 33 to get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 7:
If we divide 120 by 21, we get 5 and a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 21341.5
Deduct 105 from 120 and we're left with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Let's proceed to step 8:
When dividing 150 by 21, we get 7 with a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 21341.57
If we subtract 147 from 150, we get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Step 9:
The number 21 fits into 30 1 times, leaving a remainder of 9.
Record the quotient 1 as the next digit in the result. 
Result so far: 21341.571
If we take 21 away from 30, we end up with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Step 10:
21 can be fit into 90 4 times, resulting in a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 21341.5714
Subtract 84 from 90 to get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Step 11:
The number 21 fits into 60 2 times, leaving a remainder of 18.
Record the quotient 2 as the next digit in the result. 
Result so far: 21341.57142
The remainder is 18 after subtracting 42 from 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Moving on to step 12:
The number 21 fits into 180 8 times, leaving a remainder of 12.
Write down 8 as next digit of the result. 
Result so far: 21341.571428
If we subtract 168 from 180, we get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

On to step 13:
120 divided by 21 is 5 with a remainder of 15.
Record the quotient 5 as the next digit in the result. 
Result so far: 21341.5714285
If we take 105 away from 120, we end up with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Advancing to step 14:
150 divided by 21 is 7 with a remainder of 3.
Use 7 as the next digit of our solution. 
Result so far: 21341.57142857
Deduct 147 from 150 and we're left with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

In conclusion, the division gives 21341.57142857 with a balance of 3e-09.