286103 divided by 21 
We want to figure out the number of times 286103 can be divided by 21.

Step 1:
2 divided by 21 is 0 with a remainder of 2.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 2 leaves us with 2.
Append the next digit (8) from the dividend to 2 and continue with: 28 / 21

Going ahead to step 2:
When dividing 28 by 21, we get 1 with a remainder of 7.
Write down 1 as next digit of the result. 
Result so far: 1.0
Subtract 21 from 28 to get 7.
Grab the next digit (6) from the dividend, add it to 7, then carry on: 76 / 21

Moving on to step 3:
21 goes into 76 3 times with a remainder of 13.
Write down 3 as next digit of the result. 
Result so far: 13.0
Deduct 63 from 76 and we're left with 13.
Include the next digit (1) from the dividend after 13, then repeat: 131 / 21

Step 4:
21 can be fit into 131 6 times, resulting in a remainder of 5.
Record the quotient 6 as the next digit in the result. 
Result so far: 136.0
Subtracting 126 from 131 leaves us with 5.
Take the next digit (0) from the dividend and append it to 5, then repeat: 50 / 21

Moving on to step 5:
50 divided by 21 is 2 with a remainder of 8.
The next digit of our result is 2. 
Result so far: 1362.0
Deduct 42 from 50 and we're left with 8.
Grab the next digit (3) from the dividend, add it to 8, then carry on: 83 / 21

Advancing to step 6:
21 goes into 83 3 times with a remainder of 20.
Write down 3 as next digit of the result. 
Result so far: 13623.0
If we subtract 63 from 83, we 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 7:
When dividing 200 by 21, we get 9 with a remainder of 11.
The next digit of our result is 9. 
Result so far: 13623.9
If we take 189 away from 200, we end up 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.

Advancing to step 8:
110 divided by 21 is 5 with a remainder of 5.
The next digit of our result is 5. 
Result so far: 13623.95
If we take 105 away from 110, we end up 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 9:
21 can be fit into 50 2 times, resulting in a remainder of 8.
Record the quotient 2 as the next digit in the result. 
Result so far: 13623.952
Deduct 42 from 50 and we're left 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.

On to step 10:
21 can be fit into 80 3 times, resulting in a remainder of 17.
Put 3 as the next digit of the answer. 
Result so far: 13623.9523
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.

Going ahead to step 11:
When dividing 170 by 21, we get 8 with a remainder of 2.
Use 8 as the next digit of our solution. 
Result so far: 13623.95238
If we take 168 away from 170, we end up with 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.
Use 0 as the next digit of our solution. 
Result so far: 13623.95238
The remainder is 20 after subtracting 0 from 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

On to step 13:
When dividing 200 by 21, we get 9 with a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 13623.9523809
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.

Let's proceed to step 14:
If we divide 110 by 21, we get 5 and a remainder of 5.
Put 5 as the next digit of the answer. 
Result so far: 13623.95238095
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.

After the division, we end up with 13623.95238095 and a remainder of 5e-09.