78490469 ÷ 644 
The aim is to understand the frequency of 644 in 78490469.

On to step 1:
If we divide 7 by 644, we get 0 and a remainder of 7.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 7, we end up with 7.
Take the next digit (8) from the dividend and append it to 7, then repeat: 78 / 644

Advancing to step 2:
When dividing 78 by 644, we get 0 with a remainder of 78.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 78, we end up with 78.
Append the next digit (4) from the dividend to 78 and continue with: 784 / 644

On to step 3:
644 goes into 784 1 times with a remainder of 140.
Write down 1 as next digit of the result. 
Result so far: 1.0
If we subtract 644 from 784, we get 140.
Include the next digit (9) from the dividend after 140, then repeat: 1409 / 644

On to step 4:
644 goes into 1409 2 times with a remainder of 121.
The next digit of our result is 2. 
Result so far: 12.0
Deduct 1288 from 1409 and we're left with 121.
Bring next digit (0) of the dividend behind the 121 and repeat the process: 1210 / 644

Let's proceed to step 5:
When dividing 1210 by 644, we get 1 with a remainder of 566.
The next digit of our result is 1. 
Result so far: 121.0
The remainder is 566 after subtracting 644 from 1210.
Fetch the next digit (4) from the dividend, attach it to 566 and continue: 5664 / 644

Going ahead to step 6:
644 goes into 5664 8 times with a remainder of 512.
Use 8 as the next digit of our solution. 
Result so far: 1218.0
If we subtract 5152 from 5664, we get 512.
Bring next digit (6) of the dividend behind the 512 and repeat the process: 5126 / 644

Moving on to step 7:
The number 644 fits into 5126 7 times, leaving a remainder of 618.
The number 7 becomes the next digit in our result. 
Result so far: 12187.0
If we subtract 4508 from 5126, we get 618.
Grab the next digit (9) from the dividend, add it to 618, then carry on: 6189 / 644

On to step 8:
When dividing 6189 by 644, we get 9 with a remainder of 393.
Put 9 as the next digit of the answer. 
Result so far: 121879.0
The remainder is 393 after subtracting 5796 from 6189.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3930, and continue the process.

Moving on to step 9:
3930 divided by 644 is 6 with a remainder of 66.
Put 6 as the next digit of the answer. 
Result so far: 121879.6
If we subtract 3864 from 3930, we get 66.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

Going ahead to step 10:
When dividing 660 by 644, we get 1 with a remainder of 16.
Record the quotient 1 as the next digit in the result. 
Result so far: 121879.61
If we take 644 away from 660, we end up with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Going ahead to step 11:
If we divide 160 by 644, we get 0 and a remainder of 160.
Use 0 as the next digit of our solution. 
Result so far: 121879.61
The remainder is 160 after subtracting 0 from 160.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1600, and continue the process.

Moving on to step 12:
When dividing 1600 by 644, we get 2 with a remainder of 312.
The number 2 becomes the next digit in our result. 
Result so far: 121879.6102
If we take 1288 away from 1600, we end up with 312.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3120, and continue the process.

Going ahead to step 13:
If we divide 3120 by 644, we get 4 and a remainder of 544.
Use 4 as the next digit of our solution. 
Result so far: 121879.61024
The remainder is 544 after subtracting 2576 from 3120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5440, and continue the process.

Step 14:
644 can be fit into 5440 8 times, resulting in a remainder of 288.
The number 8 becomes the next digit in our result. 
Result so far: 121879.610248
If we subtract 5152 from 5440, we get 288.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2880, and continue the process.

Going ahead to step 15:
When dividing 2880 by 644, we get 4 with a remainder of 304.
The next digit of our result is 4. 
Result so far: 121879.6102484
Deduct 2576 from 2880 and we're left with 304.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3040, and continue the process.

Step 16:
644 can be fit into 3040 4 times, resulting in a remainder of 464.
Use 4 as the next digit of our solution. 
Result so far: 121879.61024844
If we take 2576 away from 3040, we end up with 464.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4640, and continue the process.

Our division results in 121879.61024844 with a remaining 4.64e-07.