We look at the division of 43187126 by 642 
We want to figure out the number of times 43187126 can be divided by 642.

Step 1:
If we divide 4 by 642, we get 0 and a remainder of 4.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 4 and we're left with 4.
Append the next digit (3) from the dividend to 4 and continue with: 43 / 642

Step 2:
The number 642 fits into 43 0 times, leaving a remainder of 43.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 43, we get 43.
Include the next digit (1) from the dividend after 43, then repeat: 431 / 642

On to step 3:
431 divided by 642 is 0 with a remainder of 431.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 431 to get 431.
Grab the next digit (8) from the dividend, add it to 431, then carry on: 4318 / 642

Step 4:
When dividing 4318 by 642, we get 6 with a remainder of 466.
Put 6 as the next digit of the answer. 
Result so far: 6.0
Deduct 3852 from 4318 and we're left with 466.
Grab the next digit (7) from the dividend, add it to 466, then carry on: 4667 / 642

Moving on to step 5:
The number 642 fits into 4667 7 times, leaving a remainder of 173.
Use 7 as the next digit of our solution. 
Result so far: 67.0
Subtracting 4494 from 4667 leaves us with 173.
Bring next digit (1) of the dividend behind the 173 and repeat the process: 1731 / 642

Step 6:
642 goes into 1731 2 times with a remainder of 447.
Record the quotient 2 as the next digit in the result. 
Result so far: 672.0
If we take 1284 away from 1731, we end up with 447.
Take the next digit (2) from the dividend and append it to 447, then repeat: 4472 / 642

Moving on to step 7:
When dividing 4472 by 642, we get 6 with a remainder of 620.
The next digit of our result is 6. 
Result so far: 6726.0
If we subtract 3852 from 4472, we get 620.
Grab the next digit (6) from the dividend, add it to 620, then carry on: 6206 / 642

Moving on to step 8:
When dividing 6206 by 642, we get 9 with a remainder of 428.
Use 9 as the next digit of our solution. 
Result so far: 67269.0
Subtract 5778 from 6206 to get 428.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4280, and continue the process.

Going ahead to step 9:
When dividing 4280 by 642, we get 6 with a remainder of 428.
The number 6 becomes the next digit in our result. 
Result so far: 67269.6
Subtracting 3852 from 4280 leaves us with 428.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4280, and continue the process.

Step 10:
642 can be fit into 4280 6 times, resulting in a remainder of 428.
Use 6 as the next digit of our solution. 
Result so far: 67269.66
If we take 3852 away from 4280, we end up with 428.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4280, and continue the process.

The final result is 67269.66 with a remainder of 0.428.