210857 divided by 21 
We're looking to find how many times 21 goes into 210857.

Let's proceed to step 1:
The number 21 fits into 2 0 times, leaving a remainder of 2.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 2 after subtracting 0 from 2.
Grab the next digit (1) from the dividend, add it to 2, then carry on: 21 / 21

Step 2:
21 can be fit into 21 1 times, resulting in a remainder of 0.
Put 1 as the next digit of the answer. 
Result so far: 1.0
The remainder is 0 after subtracting 21 from 21.
Take the next digit (0) from the dividend and append it to 0, then repeat: 0 / 21

Step 3:
21 goes into 0 0 times with a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 10.0
The remainder is 0 after subtracting 0 from 0.
Grab the next digit (8) from the dividend, add it to 0, then carry on: 8 / 21

Moving on to step 4:
The number 21 fits into 8 0 times, leaving a remainder of 8.
Record the quotient 0 as the next digit in the result. 
Result so far: 100.0
Subtract 0 from 8 to get 8.
Include the next digit (5) from the dividend after 8, then repeat: 85 / 21

Going ahead to step 5:
The number 21 fits into 85 4 times, leaving a remainder of 1.
The number 4 becomes the next digit in our result. 
Result so far: 1004.0
Deduct 84 from 85 and we're left with 1.
Append the next digit (7) from the dividend to 1 and continue with: 17 / 21

Advancing to step 6:
The number 21 fits into 17 0 times, leaving a remainder of 17.
The next digit of our result is 0. 
Result so far: 10040.0
Subtracting 0 from 17 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.

Advancing to step 7:
21 goes into 170 8 times with a remainder of 2.
Record the quotient 8 as the next digit in the result. 
Result so far: 10040.8
Subtract 168 from 170 to 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.

Advancing to step 8:
The number 21 fits into 20 0 times, leaving a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 10040.8
Subtract 0 from 20 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.

Advancing to step 9:
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: 10040.809
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.

Moving on to step 10:
110 divided by 21 is 5 with a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 10040.8095
Subtracting 105 from 110 leaves us with 5.
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 11:
When dividing 50 by 21, we get 2 with a remainder of 8.
The next digit of our result is 2. 
Result so far: 10040.80952
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.

Moving on to step 12:
When dividing 80 by 21, we get 3 with a remainder of 17.
Write down 3 as next digit of the result. 
Result so far: 10040.809523
If we subtract 63 from 80, we get 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Moving on to step 13:
21 goes into 170 8 times with a remainder of 2.
Write down 8 as next digit of the result. 
Result so far: 10040.8095238
Subtract 168 from 170 to 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.

Let's proceed to step 14:
The number 21 fits into 20 0 times, leaving a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 10040.8095238
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.

After the division, we end up with 10040.8095238 and a remainder of 2e-08.