We're dividing 86003216 by 21 
Our goal is to divide 86003216 by 21.

Going ahead to step 1:
If we divide 8 by 21, we get 0 and a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 8 leaves us with 8.
Append the next digit (6) from the dividend to 8 and continue with: 86 / 21

On to step 2:
21 can be fit into 86 4 times, resulting in a remainder of 2.
The next digit of our result is 4. 
Result so far: 4.0
The remainder is 2 after subtracting 84 from 86.
Grab the next digit (0) from the dividend, add it to 2, then carry on: 20 / 21

Going ahead to step 3:
If we divide 20 by 21, we get 0 and a remainder of 20.
Write down 0 as next digit of the result. 
Result so far: 40.0
If we take 0 away from 20, we end up with 20.
Include the next digit (0) from the dividend after 20, then repeat: 200 / 21

On to step 4:
200 divided by 21 is 9 with a remainder of 11.
The next digit of our result is 9. 
Result so far: 409.0
Subtracting 189 from 200 leaves us with 11.
Append the next digit (3) from the dividend to 11 and continue with: 113 / 21

Going ahead to step 5:
If we divide 113 by 21, we get 5 and a remainder of 8.
The number 5 becomes the next digit in our result. 
Result so far: 4095.0
Subtract 105 from 113 to get 8.
Include the next digit (2) from the dividend after 8, then repeat: 82 / 21

Step 6:
When dividing 82 by 21, we get 3 with a remainder of 19.
Record the quotient 3 as the next digit in the result. 
Result so far: 40953.0
Deduct 63 from 82 and we're left with 19.
Fetch the next digit (1) from the dividend, attach it to 19 and continue: 191 / 21

Moving on to step 7:
191 divided by 21 is 9 with a remainder of 2.
Record the quotient 9 as the next digit in the result. 
Result so far: 409539.0
Subtract 189 from 191 to get 2.
Grab the next digit (6) from the dividend, add it to 2, then carry on: 26 / 21

Advancing to step 8:
21 goes into 26 1 times with a remainder of 5.
Write down 1 as next digit of the result. 
Result so far: 4095391.0
If we take 21 away from 26, 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.

Going ahead to step 9:
21 can be fit into 50 2 times, resulting in a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 4095391.2
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.

Step 10:
The number 21 fits into 80 3 times, leaving a remainder of 17.
Write down 3 as next digit of the result. 
Result so far: 4095391.23
Subtracting 63 from 80 leaves us with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Advancing to step 11:
If we divide 170 by 21, we get 8 and a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 4095391.238
Subtracting 168 from 170 leaves us 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.

Step 12:
If we divide 20 by 21, we get 0 and a remainder of 20.
Use 0 as the next digit of our solution. 
Result so far: 4095391.238
If we subtract 0 from 20, 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.

Moving on to step 13:
When dividing 200 by 21, we get 9 with a remainder of 11.
Use 9 as the next digit of our solution. 
Result so far: 4095391.23809
Deduct 189 from 200 and we're left 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.

Let's proceed to step 14:
The number 21 fits into 110 5 times, leaving a remainder of 5.
The number 5 becomes the next digit in our result. 
Result so far: 4095391.238095
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.

Advancing to step 15:
The number 21 fits into 50 2 times, leaving a remainder of 8.
Use 2 as the next digit of our solution. 
Result so far: 4095391.2380952
If we take 42 away from 50, we end up 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 16:
80 divided by 21 is 3 with a remainder of 17.
Record the quotient 3 as the next digit in the result. 
Result so far: 4095391.23809523
The remainder is 17 after subtracting 63 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

The final outcome is 4095391.23809523, with a leftover of 1.7e-08.