78455905 divided by 644 
We want to figure out the number of times 78455905 can be divided by 644.

On to step 1:
If we divide 7 by 644, we get 0 and a remainder of 7.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 7 to get 7.
Append the next digit (8) from the dividend to 7 and continue with: 78 / 644

On to step 2:
If we divide 78 by 644, we get 0 and a remainder of 78.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 78 to get 78.
Take the next digit (4) from the dividend and append it to 78, then repeat: 784 / 644

Let's proceed to step 3:
If we divide 784 by 644, we get 1 and a remainder of 140.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Deduct 644 from 784 and we're left with 140.
Fetch the next digit (5) from the dividend, attach it to 140 and continue: 1405 / 644

Advancing to step 4:
644 goes into 1405 2 times with a remainder of 117.
The next digit of our result is 2. 
Result so far: 12.0
If we take 1288 away from 1405, we end up with 117.
Include the next digit (5) from the dividend after 117, then repeat: 1175 / 644

Moving on to step 5:
The number 644 fits into 1175 1 times, leaving a remainder of 531.
Use 1 as the next digit of our solution. 
Result so far: 121.0
If we subtract 644 from 1175, we get 531.
Grab the next digit (9) from the dividend, add it to 531, then carry on: 5319 / 644

Going ahead to step 6:
644 goes into 5319 8 times with a remainder of 167.
The next digit of our result is 8. 
Result so far: 1218.0
If we subtract 5152 from 5319, we get 167.
Bring next digit (0) of the dividend behind the 167 and repeat the process: 1670 / 644

Moving on to step 7:
644 goes into 1670 2 times with a remainder of 382.
The next digit of our result is 2. 
Result so far: 12182.0
Subtracting 1288 from 1670 leaves us with 382.
Take the next digit (5) from the dividend and append it to 382, then repeat: 3825 / 644

Going ahead to step 8:
644 goes into 3825 5 times with a remainder of 605.
Record the quotient 5 as the next digit in the result. 
Result so far: 121825.0
If we take 3220 away from 3825, we end up with 605.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6050, and continue the process.

Moving on to step 9:
If we divide 6050 by 644, we get 9 and a remainder of 254.
Write down 9 as next digit of the result. 
Result so far: 121825.9
The remainder is 254 after subtracting 5796 from 6050.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2540, and continue the process.

On to step 10:
2540 divided by 644 is 3 with a remainder of 608.
Put 3 as the next digit of the answer. 
Result so far: 121825.93
If we subtract 1932 from 2540, we get 608.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6080, and continue the process.

Going ahead to step 11:
The number 644 fits into 6080 9 times, leaving a remainder of 284.
Write down 9 as next digit of the result. 
Result so far: 121825.939
Subtracting 5796 from 6080 leaves us with 284.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2840, and continue the process.

Advancing to step 12:
644 goes into 2840 4 times with a remainder of 264.
Use 4 as the next digit of our solution. 
Result so far: 121825.9394
Deduct 2576 from 2840 and we're left with 264.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2640, and continue the process.

Going ahead to step 13:
The number 644 fits into 2640 4 times, leaving a remainder of 64.
The next digit of our result is 4. 
Result so far: 121825.93944
Subtract 2576 from 2640 to get 64.
Since there are no more digits in the dividend, we add a zero to the remainder making it 640, and continue the process.

After the division, we end up with 121825.93944 and a remainder of 6.4e-05.