We divide 430287 by 21
We want to figure out the number of times 430287 can be divided by 21.

Let's proceed to step 1:
21 goes into 4 0 times with a remainder of 4.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 4 after subtracting 0 from 4.
Bring next digit (3) of the dividend behind the 4 and repeat the process: 43 / 21

Advancing to step 2:
43 divided by 21 is 2 with a remainder of 1.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
Deduct 42 from 43 and we're left with 1.
Bring next digit (0) of the dividend behind the 1 and repeat the process: 10 / 21

Going ahead to step 3:
21 goes into 10 0 times with a remainder of 10.
Record the quotient 0 as the next digit in the result. 
Result so far: 20.0
Subtract 0 from 10 to get 10.
Take the next digit (2) from the dividend and append it to 10, then repeat: 102 / 21

Step 4:
102 divided by 21 is 4 with a remainder of 18.
Put 4 as the next digit of the answer. 
Result so far: 204.0
If we subtract 84 from 102, we get 18.
Bring next digit (8) of the dividend behind the 18 and repeat the process: 188 / 21

Let's proceed to step 5:
21 goes into 188 8 times with a remainder of 20.
Put 8 as the next digit of the answer. 
Result so far: 2048.0
Subtracting 168 from 188 leaves us with 20.
Fetch the next digit (7) from the dividend, attach it to 20 and continue: 207 / 21

Let's proceed to step 6:
The number 21 fits into 207 9 times, leaving a remainder of 18.
Record the quotient 9 as the next digit in the result. 
Result so far: 20489.0
Subtracting 189 from 207 leaves us with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Going ahead to step 7:
The number 21 fits into 180 8 times, leaving a remainder of 12.
Put 8 as the next digit of the answer. 
Result so far: 20489.8
Subtract 168 from 180 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.

On to step 8:
21 can be fit into 120 5 times, resulting in a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 20489.85
If we subtract 105 from 120, we get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Going ahead to step 9:
If we divide 150 by 21, we get 7 and a remainder of 3.
Write down 7 as next digit of the result. 
Result so far: 20489.857
Subtract 147 from 150 to 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.

On to step 10:
30 divided by 21 is 1 with a remainder of 9.
Record the quotient 1 as the next digit in the result. 
Result so far: 20489.8571
Subtracting 21 from 30 leaves us 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.

Going ahead to step 11:
The number 21 fits into 90 4 times, leaving a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 20489.85714
Deduct 84 from 90 and we're left with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Moving on to step 12:
If we divide 60 by 21, we get 2 and a remainder of 18.
Write down 2 as next digit of the result. 
Result so far: 20489.857142
If we take 42 away from 60, we end up with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Going ahead to step 13:
180 divided by 21 is 8 with a remainder of 12.
Record the quotient 8 as the next digit in the result. 
Result so far: 20489.8571428
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.

Going ahead to step 14:
If we divide 120 by 21, we get 5 and a remainder of 15.
Put 5 as the next digit of the answer. 
Result so far: 20489.85714285
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.

After the division, we end up with 20489.85714285 and a remainder of 1.5e-08.