644221 ÷ 75 
We want to figure out the number of times 644221 can be divided by 75.

Let's proceed to step 1:
75 can be fit into 6 0 times, resulting in a remainder of 6.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Grab the next digit (4) from the dividend, add it to 6, then carry on: 64 / 75

Advancing to step 2:
When dividing 64 by 75, we get 0 with a remainder of 64.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 64 leaves us with 64.
Take the next digit (4) from the dividend and append it to 64, then repeat: 644 / 75

Let's proceed to step 3:
If we divide 644 by 75, we get 8 and a remainder of 44.
Record the quotient 8 as the next digit in the result. 
Result so far: 8.0
Deduct 600 from 644 and we're left with 44.
Append the next digit (2) from the dividend to 44 and continue with: 442 / 75

On to step 4:
The number 75 fits into 442 5 times, leaving a remainder of 67.
Put 5 as the next digit of the answer. 
Result so far: 85.0
Deduct 375 from 442 and we're left with 67.
Bring next digit (2) of the dividend behind the 67 and repeat the process: 672 / 75

Let's proceed to step 5:
672 divided by 75 is 8 with a remainder of 72.
The number 8 becomes the next digit in our result. 
Result so far: 858.0
Subtract 600 from 672 to get 72.
Grab the next digit (1) from the dividend, add it to 72, then carry on: 721 / 75

Going ahead to step 6:
721 divided by 75 is 9 with a remainder of 46.
The number 9 becomes the next digit in our result. 
Result so far: 8589.0
If we subtract 675 from 721, we get 46.
Since there are no more digits in the dividend, we add a zero to the remainder making it 460, and continue the process.

Let's proceed to step 7:
75 can be fit into 460 6 times, resulting in a remainder of 10.
Record the quotient 6 as the next digit in the result. 
Result so far: 8589.6
The remainder is 10 after subtracting 450 from 460.
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 8:
75 can be fit into 100 1 times, resulting in a remainder of 25.
Put 1 as the next digit of the answer. 
Result so far: 8589.61
The remainder is 25 after subtracting 75 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Step 9:
75 goes into 250 3 times with a remainder of 25.
The next digit of our result is 3. 
Result so far: 8589.613
If we take 225 away from 250, we end up with 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Let's proceed to step 10:
If we divide 250 by 75, we get 3 and a remainder of 25.
The number 3 becomes the next digit in our result. 
Result so far: 8589.6133
Subtracting 225 from 250 leaves us with 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Our division results in 8589.6133 with a remaining 0.00025.