640391 divided by 75 
We're looking to find how many times 75 goes into 640391.

Step 1:
75 can be fit into 6 0 times, resulting in a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Fetch the next digit (4) from the dividend, attach it to 6 and continue: 64 / 75

Let's proceed to step 2:
The number 75 fits into 64 0 times, leaving a remainder of 64.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 64, we end up with 64.
Include the next digit (0) from the dividend after 64, then repeat: 640 / 75

Step 3:
If we divide 640 by 75, we get 8 and a remainder of 40.
Use 8 as the next digit of our solution. 
Result so far: 8.0
Subtract 600 from 640 to get 40.
Include the next digit (3) from the dividend after 40, then repeat: 403 / 75

Step 4:
75 can be fit into 403 5 times, resulting in a remainder of 28.
Put 5 as the next digit of the answer. 
Result so far: 85.0
If we take 375 away from 403, we end up with 28.
Append the next digit (9) from the dividend to 28 and continue with: 289 / 75

Let's proceed to step 5:
If we divide 289 by 75, we get 3 and a remainder of 64.
Use 3 as the next digit of our solution. 
Result so far: 853.0
If we subtract 225 from 289, we get 64.
Include the next digit (1) from the dividend after 64, then repeat: 641 / 75

Going ahead to step 6:
75 can be fit into 641 8 times, resulting in a remainder of 41.
Write down 8 as next digit of the result. 
Result so far: 8538.0
Subtract 600 from 641 to get 41.
Since there are no more digits in the dividend, we add a zero to the remainder making it 410, and continue the process.

Going ahead to step 7:
75 goes into 410 5 times with a remainder of 35.
Use 5 as the next digit of our solution. 
Result so far: 8538.5
Subtract 375 from 410 to get 35.
Since there are no more digits in the dividend, we add a zero to the remainder making it 350, and continue the process.

Moving on to step 8:
When dividing 350 by 75, we get 4 with a remainder of 50.
Record the quotient 4 as the next digit in the result. 
Result so far: 8538.54
Subtracting 300 from 350 leaves us 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.

Going ahead to step 9:
When dividing 500 by 75, we get 6 with a remainder of 50.
Put 6 as the next digit of the answer. 
Result so far: 8538.546
The remainder is 50 after subtracting 450 from 500.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

On to step 10:
75 can be fit into 500 6 times, resulting in a remainder of 50.
The number 6 becomes the next digit in our result. 
Result so far: 8538.5466
Subtract 450 from 500 to get 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

The final result is 8538.5466 with a remainder of 0.0005.