Let's divide 63879373 by 15
We want to figure out the number of times 63879373 can be divided by 15.

On to step 1:
When dividing 6 by 15, we get 0 with a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Append the next digit (3) from the dividend to 6 and continue with: 63 / 15

Let's proceed to step 2:
If we divide 63 by 15, we get 4 and a remainder of 3.
Record the quotient 4 as the next digit in the result. 
Result so far: 4.0
If we subtract 60 from 63, we get 3.
Take the next digit (8) from the dividend and append it to 3, then repeat: 38 / 15

Step 3:
The number 15 fits into 38 2 times, leaving a remainder of 8.
Write down 2 as next digit of the result. 
Result so far: 42.0
If we subtract 30 from 38, we get 8.
Include the next digit (7) from the dividend after 8, then repeat: 87 / 15

Let's proceed to step 4:
The number 15 fits into 87 5 times, leaving a remainder of 12.
Write down 5 as next digit of the result. 
Result so far: 425.0
If we take 75 away from 87, we end up with 12.
Grab the next digit (9) from the dividend, add it to 12, then carry on: 129 / 15

On to step 5:
When dividing 129 by 15, we get 8 with a remainder of 9.
Record the quotient 8 as the next digit in the result. 
Result so far: 4258.0
If we subtract 120 from 129, we get 9.
Include the next digit (3) from the dividend after 9, then repeat: 93 / 15

Going ahead to step 6:
The number 15 fits into 93 6 times, leaving a remainder of 3.
Use 6 as the next digit of our solution. 
Result so far: 42586.0
If we subtract 90 from 93, we get 3.
Take the next digit (7) from the dividend and append it to 3, then repeat: 37 / 15

Going ahead to step 7:
15 can be fit into 37 2 times, resulting in a remainder of 7.
The next digit of our result is 2. 
Result so far: 425862.0
Deduct 30 from 37 and we're left with 7.
Include the next digit (3) from the dividend after 7, then repeat: 73 / 15

Going ahead to step 8:
If we divide 73 by 15, we get 4 and a remainder of 13.
Use 4 as the next digit of our solution. 
Result so far: 4258624.0
The remainder is 13 after subtracting 60 from 73.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Let's proceed to step 9:
When dividing 130 by 15, we get 8 with a remainder of 10.
Write down 8 as next digit of the result. 
Result so far: 4258624.8
If we take 120 away from 130, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

On to step 10:
The number 15 fits into 100 6 times, leaving a remainder of 10.
The next digit of our result is 6. 
Result so far: 4258624.86
Subtract 90 from 100 to 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.

Advancing to step 11:
The number 15 fits into 100 6 times, leaving a remainder of 10.
The number 6 becomes the next digit in our result. 
Result so far: 4258624.866
Deduct 90 from 100 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

The final outcome is 4258624.866, with a leftover of 0.001.