We're dividing 21515684 by 78 
Let's see how many times 78 fits into 21515684.

Let's proceed to step 1:
The number 78 fits into 2 0 times, leaving 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 (1) from the dividend and append it to 2, then repeat: 21 / 78

Step 2:
78 goes into 21 0 times with a remainder of 21.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 21, we end up with 21.
Append the next digit (5) from the dividend to 21 and continue with: 215 / 78

Going ahead to step 3:
78 can be fit into 215 2 times, resulting in a remainder of 59.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
If we subtract 156 from 215, we get 59.
Fetch the next digit (1) from the dividend, attach it to 59 and continue: 591 / 78

On to step 4:
78 can be fit into 591 7 times, resulting in a remainder of 45.
Record the quotient 7 as the next digit in the result. 
Result so far: 27.0
If we subtract 546 from 591, we get 45.
Append the next digit (5) from the dividend to 45 and continue with: 455 / 78

Step 5:
The number 78 fits into 455 5 times, leaving a remainder of 65.
Write down 5 as next digit of the result. 
Result so far: 275.0
Subtracting 390 from 455 leaves us with 65.
Append the next digit (6) from the dividend to 65 and continue with: 656 / 78

Step 6:
If we divide 656 by 78, we get 8 and a remainder of 32.
Use 8 as the next digit of our solution. 
Result so far: 2758.0
Subtracting 624 from 656 leaves us with 32.
Grab the next digit (8) from the dividend, add it to 32, then carry on: 328 / 78

Let's proceed to step 7:
When dividing 328 by 78, we get 4 with a remainder of 16.
The number 4 becomes the next digit in our result. 
Result so far: 27584.0
If we take 312 away from 328, we end up with 16.
Grab the next digit (4) from the dividend, add it to 16, then carry on: 164 / 78

Step 8:
78 can be fit into 164 2 times, resulting in a remainder of 8.
Write down 2 as next digit of the result. 
Result so far: 275842.0
The remainder is 8 after subtracting 156 from 164.
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 9:
80 divided by 78 is 1 with a remainder of 2.
Record the quotient 1 as the next digit in the result. 
Result so far: 275842.1
Subtract 78 from 80 to get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Moving on to step 10:
20 divided by 78 is 0 with a remainder of 20.
Use 0 as the next digit of our solution. 
Result so far: 275842.1
Subtracting 0 from 20 leaves us with 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 11:
The number 78 fits into 200 2 times, leaving a remainder of 44.
Use 2 as the next digit of our solution. 
Result so far: 275842.102
Subtract 156 from 200 to get 44.
Since there are no more digits in the dividend, we add a zero to the remainder making it 440, and continue the process.

Advancing to step 12:
78 goes into 440 5 times with a remainder of 50.
The number 5 becomes the next digit in our result. 
Result so far: 275842.1025
Deduct 390 from 440 and we're left with 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

Moving on to step 13:
If we divide 500 by 78, we get 6 and a remainder of 32.
The next digit of our result is 6. 
Result so far: 275842.10256
If we subtract 468 from 500, we get 32.
Since there are no more digits in the dividend, we add a zero to the remainder making it 320, and continue the process.

Moving on to step 14:
78 can be fit into 320 4 times, resulting in a remainder of 8.
The next digit of our result is 4. 
Result so far: 275842.102564
If we subtract 312 from 320, we get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Let's proceed to step 15:
80 divided by 78 is 1 with a remainder of 2.
The number 1 becomes the next digit in our result. 
Result so far: 275842.1025641
Subtract 78 from 80 to get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Moving on to step 16:
If we divide 20 by 78, we get 0 and a remainder of 20.
Use 0 as the next digit of our solution. 
Result so far: 275842.1025641
Subtract 0 from 20 to 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.

The final outcome is 275842.1025641, with a leftover of 2e-08.