We look at the division of 86440 by 21 
Let's see how many times 21 fits into 86440.

Going ahead to step 1:
The number 21 fits into 8 0 times, leaving a remainder of 8.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 8, we end up with 8.
Bring next digit (6) of the dividend behind the 8 and repeat the process: 86 / 21

Moving on to step 2:
If we divide 86 by 21, we get 4 and a remainder of 2.
Write down 4 as next digit of the result. 
Result so far: 4.0
Subtracting 84 from 86 leaves us with 2.
Append the next digit (4) from the dividend to 2 and continue with: 24 / 21

Let's proceed to step 3:
When dividing 24 by 21, we get 1 with a remainder of 3.
Write down 1 as next digit of the result. 
Result so far: 41.0
If we subtract 21 from 24, we get 3.
Grab the next digit (4) from the dividend, add it to 3, then carry on: 34 / 21

Advancing to step 4:
21 can be fit into 34 1 times, resulting in a remainder of 13.
The next digit of our result is 1. 
Result so far: 411.0
Subtract 21 from 34 to get 13.
Bring next digit (0) of the dividend behind the 13 and repeat the process: 130 / 21

Step 5:
When dividing 130 by 21, we get 6 with a remainder of 4.
Use 6 as the next digit of our solution. 
Result so far: 4116.0
The remainder is 4 after subtracting 126 from 130.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Advancing to step 6:
When dividing 40 by 21, we get 1 with a remainder of 19.
Write down 1 as next digit of the result. 
Result so far: 4116.1
If we subtract 21 from 40, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Step 7:
The number 21 fits into 190 9 times, leaving a remainder of 1.
The next digit of our result is 9. 
Result so far: 4116.19
If we subtract 189 from 190, we get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 8:
When dividing 10 by 21, we get 0 with a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 4116.19
If we subtract 0 from 10, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 9:
21 goes into 100 4 times with a remainder of 16.
Write down 4 as next digit of the result. 
Result so far: 4116.1904
Subtracting 84 from 100 leaves us with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Advancing to step 10:
The number 21 fits into 160 7 times, leaving a remainder of 13.
The next digit of our result is 7. 
Result so far: 4116.19047
Subtracting 147 from 160 leaves us with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Step 11:
If we divide 130 by 21, we get 6 and a remainder of 4.
Put 6 as the next digit of the answer. 
Result so far: 4116.190476
Subtracting 126 from 130 leaves us with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Let's proceed to step 12:
40 divided by 21 is 1 with a remainder of 19.
Write down 1 as next digit of the result. 
Result so far: 4116.1904761
Subtracting 21 from 40 leaves us with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Step 13:
190 divided by 21 is 9 with a remainder of 1.
Use 9 as the next digit of our solution. 
Result so far: 4116.19047619
Subtract 189 from 190 to get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

The final outcome is 4116.19047619, with a leftover of 1e-09.