We look at the division of 363887 by 21 
We want to figure out the number of times 363887 can be divided by 21.

Let's proceed to step 1:
21 goes into 3 0 times with a remainder of 3.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Take the next digit (6) from the dividend and append it to 3, then repeat: 36 / 21

On to step 2:
21 goes into 36 1 times with a remainder of 15.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
If we take 21 away from 36, we end up with 15.
Grab the next digit (3) from the dividend, add it to 15, then carry on: 153 / 21

Step 3:
When dividing 153 by 21, we get 7 with a remainder of 6.
Use 7 as the next digit of our solution. 
Result so far: 17.0
Subtract 147 from 153 to get 6.
Include the next digit (8) from the dividend after 6, then repeat: 68 / 21

Advancing to step 4:
68 divided by 21 is 3 with a remainder of 5.
Put 3 as the next digit of the answer. 
Result so far: 173.0
Subtracting 63 from 68 leaves us with 5.
Fetch the next digit (8) from the dividend, attach it to 5 and continue: 58 / 21

On to step 5:
21 goes into 58 2 times with a remainder of 16.
Record the quotient 2 as the next digit in the result. 
Result so far: 1732.0
Deduct 42 from 58 and we're left with 16.
Fetch the next digit (7) from the dividend, attach it to 16 and continue: 167 / 21

On to step 6:
21 goes into 167 7 times with a remainder of 20.
The number 7 becomes the next digit in our result. 
Result so far: 17327.0
Subtract 147 from 167 to get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Going ahead to step 7:
The number 21 fits into 200 9 times, leaving a remainder of 11.
Use 9 as the next digit of our solution. 
Result so far: 17327.9
If we subtract 189 from 200, we 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.

Moving on to step 8:
If we divide 110 by 21, we get 5 and a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 17327.95
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.

Moving on to step 9:
The number 21 fits into 50 2 times, leaving a remainder of 8.
Use 2 as the next digit of our solution. 
Result so far: 17327.952
If we subtract 42 from 50, we get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Moving on to step 10:
The number 21 fits into 80 3 times, leaving a remainder of 17.
The number 3 becomes the next digit in our result. 
Result so far: 17327.9523
Deduct 63 from 80 and we're left 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.

Going ahead to step 11:
When dividing 170 by 21, we get 8 with a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 17327.95238
If we subtract 168 from 170, we get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

On to step 12:
21 can be fit into 20 0 times, resulting in a remainder of 20.
Put 0 as the next digit of the answer. 
Result so far: 17327.95238
Deduct 0 from 20 and we're left 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.

Going ahead to step 13:
If we divide 200 by 21, we get 9 and a remainder of 11.
Put 9 as the next digit of the answer. 
Result so far: 17327.9523809
Deduct 189 from 200 and we're left with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Going ahead to step 14:
21 goes into 110 5 times with a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 17327.95238095
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.

Our division results in 17327.95238095 with a remaining 5e-09.