We look at the division of 12401581 by 646 
We want to figure out the number of times 12401581 can be divided by 646.

Let's proceed to step 1:
1 divided by 646 is 0 with a remainder of 1.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 1, we get 1.
Append the next digit (2) from the dividend to 1 and continue with: 12 / 646

Let's proceed to step 2:
12 divided by 646 is 0 with a remainder of 12.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 12 after subtracting 0 from 12.
Include the next digit (4) from the dividend after 12, then repeat: 124 / 646

Going ahead to step 3:
If we divide 124 by 646, we get 0 and a remainder of 124.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 124, we end up with 124.
Take the next digit (0) from the dividend and append it to 124, then repeat: 1240 / 646

Moving on to step 4:
646 goes into 1240 1 times with a remainder of 594.
Put 1 as the next digit of the answer. 
Result so far: 1.0
Deduct 646 from 1240 and we're left with 594.
Bring next digit (1) of the dividend behind the 594 and repeat the process: 5941 / 646

Step 5:
If we divide 5941 by 646, we get 9 and a remainder of 127.
Write down 9 as next digit of the result. 
Result so far: 19.0
Deduct 5814 from 5941 and we're left with 127.
Include the next digit (5) from the dividend after 127, then repeat: 1275 / 646

Step 6:
If we divide 1275 by 646, we get 1 and a remainder of 629.
The next digit of our result is 1. 
Result so far: 191.0
If we take 646 away from 1275, we end up with 629.
Grab the next digit (8) from the dividend, add it to 629, then carry on: 6298 / 646

On to step 7:
The number 646 fits into 6298 9 times, leaving a remainder of 484.
Use 9 as the next digit of our solution. 
Result so far: 1919.0
The remainder is 484 after subtracting 5814 from 6298.
Include the next digit (1) from the dividend after 484, then repeat: 4841 / 646

Advancing to step 8:
When dividing 4841 by 646, we get 7 with a remainder of 319.
Use 7 as the next digit of our solution. 
Result so far: 19197.0
Subtract 4522 from 4841 to get 319.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3190, and continue the process.

Step 9:
When dividing 3190 by 646, we get 4 with a remainder of 606.
Write down 4 as next digit of the result. 
Result so far: 19197.4
If we subtract 2584 from 3190, we get 606.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6060, and continue the process.

Step 10:
The number 646 fits into 6060 9 times, leaving a remainder of 246.
The next digit of our result is 9. 
Result so far: 19197.49
Subtract 5814 from 6060 to get 246.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2460, and continue the process.

On to step 11:
2460 divided by 646 is 3 with a remainder of 522.
Put 3 as the next digit of the answer. 
Result so far: 19197.493
Deduct 1938 from 2460 and we're left with 522.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5220, and continue the process.

On to step 12:
When dividing 5220 by 646, we get 8 with a remainder of 52.
Use 8 as the next digit of our solution. 
Result so far: 19197.4938
If we take 5168 away from 5220, we end up with 52.
Since there are no more digits in the dividend, we add a zero to the remainder making it 520, and continue the process.

Let's proceed to step 13:
If we divide 520 by 646, we get 0 and a remainder of 520.
Write down 0 as next digit of the result. 
Result so far: 19197.4938
Subtracting 0 from 520 leaves us with 520.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5200, and continue the process.

On to step 14:
The number 646 fits into 5200 8 times, leaving a remainder of 32.
The number 8 becomes the next digit in our result. 
Result so far: 19197.493808
Deduct 5168 from 5200 and we're left with 32.
Since there are no more digits in the dividend, we add a zero to the remainder making it 320, and continue the process.

Advancing to step 15:
646 goes into 320 0 times with a remainder of 320.
Record the quotient 0 as the next digit in the result. 
Result so far: 19197.493808
Subtracting 0 from 320 leaves us with 320.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3200, and continue the process.

Moving on to step 16:
The number 646 fits into 3200 4 times, leaving a remainder of 616.
The next digit of our result is 4. 
Result so far: 19197.49380804
If we take 2584 away from 3200, we end up with 616.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6160, and continue the process.

The final result is 19197.49380804 with a remainder of 6.16e-07.