87495557 ÷ 644 
The aim is to understand the frequency of 644 in 87495557.

Let's proceed to step 1:
8 divided by 644 is 0 with a remainder of 8.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 8, we end up with 8.
Append the next digit (7) from the dividend to 8 and continue with: 87 / 644

Step 2:
When dividing 87 by 644, we get 0 with a remainder of 87.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 87 leaves us with 87.
Include the next digit (4) from the dividend after 87, then repeat: 874 / 644

Advancing to step 3:
The number 644 fits into 874 1 times, leaving a remainder of 230.
Put 1 as the next digit of the answer. 
Result so far: 1.0
The remainder is 230 after subtracting 644 from 874.
Bring next digit (9) of the dividend behind the 230 and repeat the process: 2309 / 644

Advancing to step 4:
When dividing 2309 by 644, we get 3 with a remainder of 377.
Use 3 as the next digit of our solution. 
Result so far: 13.0
The remainder is 377 after subtracting 1932 from 2309.
Fetch the next digit (5) from the dividend, attach it to 377 and continue: 3775 / 644

On to step 5:
644 goes into 3775 5 times with a remainder of 555.
Record the quotient 5 as the next digit in the result. 
Result so far: 135.0
Deduct 3220 from 3775 and we're left with 555.
Take the next digit (5) from the dividend and append it to 555, then repeat: 5555 / 644

Going ahead to step 6:
644 can be fit into 5555 8 times, resulting in a remainder of 403.
Use 8 as the next digit of our solution. 
Result so far: 1358.0
Subtract 5152 from 5555 to get 403.
Bring next digit (5) of the dividend behind the 403 and repeat the process: 4035 / 644

Advancing to step 7:
644 can be fit into 4035 6 times, resulting in a remainder of 171.
The next digit of our result is 6. 
Result so far: 13586.0
If we subtract 3864 from 4035, we get 171.
Bring next digit (7) of the dividend behind the 171 and repeat the process: 1717 / 644

Step 8:
When dividing 1717 by 644, we get 2 with a remainder of 429.
The next digit of our result is 2. 
Result so far: 135862.0
If we subtract 1288 from 1717, we get 429.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4290, and continue the process.

On to step 9:
When dividing 4290 by 644, we get 6 with a remainder of 426.
Use 6 as the next digit of our solution. 
Result so far: 135862.6
If we subtract 3864 from 4290, we get 426.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4260, and continue the process.

Step 10:
The number 644 fits into 4260 6 times, leaving a remainder of 396.
The number 6 becomes the next digit in our result. 
Result so far: 135862.66
The remainder is 396 after subtracting 3864 from 4260.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3960, and continue the process.

Our division results in 135862.66 with a remaining 0.396.