285891 divided by 21 
Let's see how many times 21 fits into 285891.

On to step 1:
21 goes into 2 0 times with a remainder of 2.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 2, we end up with 2.
Take the next digit (8) from the dividend and append it to 2, then repeat: 28 / 21

Step 2:
The number 21 fits into 28 1 times, leaving a remainder of 7.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
If we subtract 21 from 28, we get 7.
Fetch the next digit (5) from the dividend, attach it to 7 and continue: 75 / 21

Let's proceed to step 3:
75 divided by 21 is 3 with a remainder of 12.
Use 3 as the next digit of our solution. 
Result so far: 13.0
Deduct 63 from 75 and we're left with 12.
Take the next digit (8) from the dividend and append it to 12, then repeat: 128 / 21

Going ahead to step 4:
21 goes into 128 6 times with a remainder of 2.
The next digit of our result is 6. 
Result so far: 136.0
The remainder is 2 after subtracting 126 from 128.
Take the next digit (9) from the dividend and append it to 2, then repeat: 29 / 21

Advancing to step 5:
If we divide 29 by 21, we get 1 and a remainder of 8.
Use 1 as the next digit of our solution. 
Result so far: 1361.0
Deduct 21 from 29 and we're left with 8.
Fetch the next digit (1) from the dividend, attach it to 8 and continue: 81 / 21

On to step 6:
The number 21 fits into 81 3 times, leaving a remainder of 18.
Use 3 as the next digit of our solution. 
Result so far: 13613.0
If we take 63 away from 81, 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.

Moving on to step 7:
When dividing 180 by 21, we get 8 with a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 13613.8
If we take 168 away from 180, we end up with 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 8:
The number 21 fits into 120 5 times, leaving a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 13613.85
The remainder is 15 after subtracting 105 from 120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Let's proceed to step 9:
21 goes into 150 7 times with a remainder of 3.
Use 7 as the next digit of our solution. 
Result so far: 13613.857
If we subtract 147 from 150, we 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.
Put 1 as the next digit of the answer. 
Result so far: 13613.8571
If we take 21 away from 30, we end up 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.

Step 11:
90 divided by 21 is 4 with a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 13613.85714
If we subtract 84 from 90, we get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Step 12:
21 goes into 60 2 times with a remainder of 18.
The next digit of our result is 2. 
Result so far: 13613.857142
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:
21 can be fit into 180 8 times, resulting in a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 13613.8571428
The remainder is 12 after subtracting 168 from 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Moving on to step 14:
When dividing 120 by 21, we get 5 with a remainder of 15.
Put 5 as the next digit of the answer. 
Result so far: 13613.85714285
Subtracting 105 from 120 leaves us 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.

The final outcome is 13613.85714285, with a leftover of 1.5e-08.