We divide 903861 by 21
We want to figure out the number of times 903861 can be divided by 21.

Let's proceed to step 1:
21 goes into 9 0 times with a remainder of 9.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 9, we end up with 9.
Append the next digit (0) from the dividend to 9 and continue with: 90 / 21

Going ahead to step 2:
90 divided by 21 is 4 with a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 4.0
If we subtract 84 from 90, we get 6.
Bring next digit (3) of the dividend behind the 6 and repeat the process: 63 / 21

On to step 3:
21 can be fit into 63 3 times, resulting in a remainder of 0.
Write down 3 as next digit of the result. 
Result so far: 43.0
The remainder is 0 after subtracting 63 from 63.
Bring next digit (8) of the dividend behind the 0 and repeat the process: 8 / 21

Going ahead to step 4:
If we divide 8 by 21, we get 0 and a remainder of 8.
Put 0 as the next digit of the answer. 
Result so far: 430.0
Subtracting 0 from 8 leaves us with 8.
Grab the next digit (6) from the dividend, add it to 8, then carry on: 86 / 21

Going ahead to step 5:
21 goes into 86 4 times with a remainder of 2.
The next digit of our result is 4. 
Result so far: 4304.0
If we subtract 84 from 86, we get 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 21

On to step 6:
The number 21 fits into 21 1 times, leaving a remainder of 0.
The next digit of our result is 1. 
Result so far: 43041.0
Subtracting 21 from 21 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Moving on to step 7:
21 can be fit into 0 0 times, resulting in a remainder of 0.
The next digit of our result is 0. 
Result so far: 43041.0
Subtract 0 from 0 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 8:
When dividing 0 by 21, we get 0 with a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 43041.0
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final result is 43041.0 with a remainder of 0.0.