64253385 divided by 644 
We want to divide 64253385 by 644.

Moving on to step 1:
6 divided by 644 is 0 with a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Include the next digit (4) from the dividend after 6, then repeat: 64 / 644

Advancing to step 2:
The number 644 fits into 64 0 times, leaving a remainder of 64.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 64 and we're left with 64.
Fetch the next digit (2) from the dividend, attach it to 64 and continue: 642 / 644

Step 3:
644 goes into 642 0 times with a remainder of 642.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 642, we get 642.
Fetch the next digit (5) from the dividend, attach it to 642 and continue: 6425 / 644

Moving on to step 4:
644 can be fit into 6425 9 times, resulting in a remainder of 629.
Use 9 as the next digit of our solution. 
Result so far: 9.0
Deduct 5796 from 6425 and we're left with 629.
Bring next digit (3) of the dividend behind the 629 and repeat the process: 6293 / 644

Going ahead to step 5:
644 can be fit into 6293 9 times, resulting in a remainder of 497.
Put 9 as the next digit of the answer. 
Result so far: 99.0
Subtracting 5796 from 6293 leaves us with 497.
Append the next digit (3) from the dividend to 497 and continue with: 4973 / 644

Advancing to step 6:
644 can be fit into 4973 7 times, resulting in a remainder of 465.
The next digit of our result is 7. 
Result so far: 997.0
If we subtract 4508 from 4973, we get 465.
Fetch the next digit (8) from the dividend, attach it to 465 and continue: 4658 / 644

Moving on to step 7:
644 can be fit into 4658 7 times, resulting in a remainder of 150.
The number 7 becomes the next digit in our result. 
Result so far: 9977.0
If we take 4508 away from 4658, we end up with 150.
Append the next digit (5) from the dividend to 150 and continue with: 1505 / 644

Moving on to step 8:
If we divide 1505 by 644, we get 2 and a remainder of 217.
Write down 2 as next digit of the result. 
Result so far: 99772.0
If we take 1288 away from 1505, we end up with 217.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2170, and continue the process.

Advancing to step 9:
644 can be fit into 2170 3 times, resulting in a remainder of 238.
Write down 3 as next digit of the result. 
Result so far: 99772.3
If we subtract 1932 from 2170, we get 238.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2380, and continue the process.

Going ahead to step 10:
644 goes into 2380 3 times with a remainder of 448.
The number 3 becomes the next digit in our result. 
Result so far: 99772.33
If we take 1932 away from 2380, we end up with 448.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4480, and continue the process.

The final result is 99772.33 with a remainder of 0.448.