286489 ÷ 21 
We want to figure out the number of times 286489 can be divided by 21.

Moving on to step 1:
When dividing 2 by 21, we get 0 with a remainder of 2.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 2 to get 2.
Fetch the next digit (8) from the dividend, attach it to 2 and continue: 28 / 21

Step 2:
28 divided by 21 is 1 with a remainder of 7.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Subtracting 21 from 28 leaves us with 7.
Take the next digit (6) from the dividend and append it to 7, then repeat: 76 / 21

Step 3:
The number 21 fits into 76 3 times, leaving a remainder of 13.
The number 3 becomes the next digit in our result. 
Result so far: 13.0
Subtract 63 from 76 to get 13.
Grab the next digit (4) from the dividend, add it to 13, then carry on: 134 / 21

Moving on to step 4:
If we divide 134 by 21, we get 6 and a remainder of 8.
Use 6 as the next digit of our solution. 
Result so far: 136.0
If we subtract 126 from 134, we get 8.
Fetch the next digit (8) from the dividend, attach it to 8 and continue: 88 / 21

Advancing to step 5:
21 can be fit into 88 4 times, resulting in a remainder of 4.
Use 4 as the next digit of our solution. 
Result so far: 1364.0
If we take 84 away from 88, we end up with 4.
Bring next digit (9) of the dividend behind the 4 and repeat the process: 49 / 21

On to step 6:
21 goes into 49 2 times with a remainder of 7.
Write down 2 as next digit of the result. 
Result so far: 13642.0
Subtract 42 from 49 to get 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Moving on to step 7:
21 goes into 70 3 times with a remainder of 7.
Write down 3 as next digit of the result. 
Result so far: 13642.3
Subtract 63 from 70 to get 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Moving on to step 8:
21 can be fit into 70 3 times, resulting in a remainder of 7.
Write down 3 as next digit of the result. 
Result so far: 13642.33
Subtracting 63 from 70 leaves us with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

The final outcome is 13642.33, with a leftover of 0.007.