Let's divide 56573887 by 644
The aim is to understand the frequency of 644 in 56573887.

On to step 1:
When dividing 5 by 644, we get 0 with a remainder of 5.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 5, we end up with 5.
Grab the next digit (6) from the dividend, add it to 5, then carry on: 56 / 644

Moving on to step 2:
644 goes into 56 0 times with a remainder of 56.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 56, we get 56.
Take the next digit (5) from the dividend and append it to 56, then repeat: 565 / 644

Moving on to step 3:
The number 644 fits into 565 0 times, leaving a remainder of 565.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 565, we get 565.
Take the next digit (7) from the dividend and append it to 565, then repeat: 5657 / 644

Moving on to step 4:
5657 divided by 644 is 8 with a remainder of 505.
The next digit of our result is 8. 
Result so far: 8.0
Deduct 5152 from 5657 and we're left with 505.
Bring next digit (3) of the dividend behind the 505 and repeat the process: 5053 / 644

On to step 5:
When dividing 5053 by 644, we get 7 with a remainder of 545.
Use 7 as the next digit of our solution. 
Result so far: 87.0
If we take 4508 away from 5053, we end up with 545.
Take the next digit (8) from the dividend and append it to 545, then repeat: 5458 / 644

Step 6:
644 goes into 5458 8 times with a remainder of 306.
Use 8 as the next digit of our solution. 
Result so far: 878.0
If we take 5152 away from 5458, we end up with 306.
Append the next digit (8) from the dividend to 306 and continue with: 3068 / 644

Moving on to step 7:
When dividing 3068 by 644, we get 4 with a remainder of 492.
The next digit of our result is 4. 
Result so far: 8784.0
Subtracting 2576 from 3068 leaves us with 492.
Bring next digit (7) of the dividend behind the 492 and repeat the process: 4927 / 644

Let's proceed to step 8:
If we divide 4927 by 644, we get 7 and a remainder of 419.
Use 7 as the next digit of our solution. 
Result so far: 87847.0
Subtracting 4508 from 4927 leaves us with 419.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4190, and continue the process.

On to step 9:
If we divide 4190 by 644, we get 6 and a remainder of 326.
Put 6 as the next digit of the answer. 
Result so far: 87847.6
Deduct 3864 from 4190 and we're left with 326.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3260, and continue the process.

Going ahead to step 10:
3260 divided by 644 is 5 with a remainder of 40.
Put 5 as the next digit of the answer. 
Result so far: 87847.65
If we subtract 3220 from 3260, we get 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Advancing to step 11:
644 goes into 400 0 times with a remainder of 400.
The next digit of our result is 0. 
Result so far: 87847.65
Deduct 0 from 400 and we're left with 400.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4000, and continue the process.

Going ahead to step 12:
When dividing 4000 by 644, we get 6 with a remainder of 136.
Put 6 as the next digit of the answer. 
Result so far: 87847.6506
Subtracting 3864 from 4000 leaves us with 136.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1360, and continue the process.

Advancing to step 13:
When dividing 1360 by 644, we get 2 with a remainder of 72.
Put 2 as the next digit of the answer. 
Result so far: 87847.65062
Subtract 1288 from 1360 to get 72.
Since there are no more digits in the dividend, we add a zero to the remainder making it 720, and continue the process.

Advancing to step 14:
If we divide 720 by 644, we get 1 and a remainder of 76.
Put 1 as the next digit of the answer. 
Result so far: 87847.650621
Subtracting 644 from 720 leaves us with 76.
Since there are no more digits in the dividend, we add a zero to the remainder making it 760, and continue the process.

Step 15:
The number 644 fits into 760 1 times, leaving a remainder of 116.
The next digit of our result is 1. 
Result so far: 87847.6506211
Subtracting 644 from 760 leaves us with 116.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1160, and continue the process.

The final result is 87847.6506211 with a remainder of 1.16e-06.