16418960 ÷ 644 
The aim is to understand the frequency of 644 in 16418960.

Advancing to step 1:
The number 644 fits into 1 0 times, leaving a remainder of 1.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 1 to get 1.
Fetch the next digit (6) from the dividend, attach it to 1 and continue: 16 / 644

Advancing to step 2:
When dividing 16 by 644, we get 0 with a remainder of 16.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 16 after subtracting 0 from 16.
Take the next digit (4) from the dividend and append it to 16, then repeat: 164 / 644

Going ahead to step 3:
If we divide 164 by 644, we get 0 and a remainder of 164.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 164 after subtracting 0 from 164.
Fetch the next digit (1) from the dividend, attach it to 164 and continue: 1641 / 644

Going ahead to step 4:
644 can be fit into 1641 2 times, resulting in a remainder of 353.
The next digit of our result is 2. 
Result so far: 2.0
Deduct 1288 from 1641 and we're left with 353.
Grab the next digit (8) from the dividend, add it to 353, then carry on: 3538 / 644

Moving on to step 5:
The number 644 fits into 3538 5 times, leaving a remainder of 318.
Use 5 as the next digit of our solution. 
Result so far: 25.0
Subtract 3220 from 3538 to get 318.
Take the next digit (9) from the dividend and append it to 318, then repeat: 3189 / 644

Going ahead to step 6:
The number 644 fits into 3189 4 times, leaving a remainder of 613.
Put 4 as the next digit of the answer. 
Result so far: 254.0
The remainder is 613 after subtracting 2576 from 3189.
Take the next digit (6) from the dividend and append it to 613, then repeat: 6136 / 644

Step 7:
If we divide 6136 by 644, we get 9 and a remainder of 340.
Record the quotient 9 as the next digit in the result. 
Result so far: 2549.0
Subtract 5796 from 6136 to get 340.
Take the next digit (0) from the dividend and append it to 340, then repeat: 3400 / 644

Step 8:
The number 644 fits into 3400 5 times, leaving a remainder of 180.
The next digit of our result is 5. 
Result so far: 25495.0
Subtract 3220 from 3400 to get 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1800, and continue the process.

Step 9:
644 goes into 1800 2 times with a remainder of 512.
The number 2 becomes the next digit in our result. 
Result so far: 25495.2
Subtract 1288 from 1800 to get 512.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5120, and continue the process.

Moving on to step 10:
The number 644 fits into 5120 7 times, leaving a remainder of 612.
Record the quotient 7 as the next digit in the result. 
Result so far: 25495.27
Deduct 4508 from 5120 and we're left with 612.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6120, and continue the process.

Advancing to step 11:
When dividing 6120 by 644, we get 9 with a remainder of 324.
Use 9 as the next digit of our solution. 
Result so far: 25495.279
Subtracting 5796 from 6120 leaves us with 324.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3240, and continue the process.

On to step 12:
When dividing 3240 by 644, we get 5 with a remainder of 20.
Record the quotient 5 as the next digit in the result. 
Result so far: 25495.2795
The remainder is 20 after subtracting 3220 from 3240.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Step 13:
When dividing 200 by 644, we get 0 with a remainder of 200.
Record the quotient 0 as the next digit in the result. 
Result so far: 25495.2795
The remainder is 200 after subtracting 0 from 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2000, and continue the process.

On to step 14:
2000 divided by 644 is 3 with a remainder of 68.
The number 3 becomes the next digit in our result. 
Result so far: 25495.279503
Subtracting 1932 from 2000 leaves us with 68.
Since there are no more digits in the dividend, we add a zero to the remainder making it 680, and continue the process.

Step 15:
644 goes into 680 1 times with a remainder of 36.
The number 1 becomes the next digit in our result. 
Result so far: 25495.2795031
If we take 644 away from 680, we end up with 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

Step 16:
360 divided by 644 is 0 with a remainder of 360.
The next digit of our result is 0. 
Result so far: 25495.2795031
If we take 0 away from 360, we end up with 360.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3600, and continue the process.

In conclusion, the division gives 25495.2795031 with a balance of 3.6e-07.