We look at the division of 89890115 by 645 
The aim is to understand the frequency of 645 in 89890115.

On to step 1:
645 goes into 8 0 times with a remainder of 8.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 8 to get 8.
Bring next digit (9) of the dividend behind the 8 and repeat the process: 89 / 645

On to step 2:
The number 645 fits into 89 0 times, leaving a remainder of 89.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 89 and we're left with 89.
Take the next digit (8) from the dividend and append it to 89, then repeat: 898 / 645

On to step 3:
645 can be fit into 898 1 times, resulting in a remainder of 253.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Deduct 645 from 898 and we're left with 253.
Bring next digit (9) of the dividend behind the 253 and repeat the process: 2539 / 645

Moving on to step 4:
2539 divided by 645 is 3 with a remainder of 604.
Write down 3 as next digit of the result. 
Result so far: 13.0
The remainder is 604 after subtracting 1935 from 2539.
Take the next digit (0) from the dividend and append it to 604, then repeat: 6040 / 645

Moving on to step 5:
645 goes into 6040 9 times with a remainder of 235.
Write down 9 as next digit of the result. 
Result so far: 139.0
If we take 5805 away from 6040, we end up with 235.
Append the next digit (1) from the dividend to 235 and continue with: 2351 / 645

Let's proceed to step 6:
2351 divided by 645 is 3 with a remainder of 416.
The number 3 becomes the next digit in our result. 
Result so far: 1393.0
If we take 1935 away from 2351, we end up with 416.
Fetch the next digit (1) from the dividend, attach it to 416 and continue: 4161 / 645

On to step 7:
4161 divided by 645 is 6 with a remainder of 291.
Write down 6 as next digit of the result. 
Result so far: 13936.0
If we take 3870 away from 4161, we end up with 291.
Bring next digit (5) of the dividend behind the 291 and repeat the process: 2915 / 645

On to step 8:
2915 divided by 645 is 4 with a remainder of 335.
Write down 4 as next digit of the result. 
Result so far: 139364.0
If we subtract 2580 from 2915, we get 335.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3350, and continue the process.

Step 9:
645 goes into 3350 5 times with a remainder of 125.
Put 5 as the next digit of the answer. 
Result so far: 139364.5
Deduct 3225 from 3350 and we're left with 125.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1250, and continue the process.

Step 10:
When dividing 1250 by 645, we get 1 with a remainder of 605.
The number 1 becomes the next digit in our result. 
Result so far: 139364.51
Subtract 645 from 1250 to get 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 11:
645 goes into 6050 9 times with a remainder of 245.
The number 9 becomes the next digit in our result. 
Result so far: 139364.519
If we subtract 5805 from 6050, we get 245.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2450, and continue the process.

On to step 12:
If we divide 2450 by 645, we get 3 and a remainder of 515.
The next digit of our result is 3. 
Result so far: 139364.5193
If we subtract 1935 from 2450, we get 515.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5150, and continue the process.

Let's proceed to step 13:
5150 divided by 645 is 7 with a remainder of 635.
Use 7 as the next digit of our solution. 
Result so far: 139364.51937
Deduct 4515 from 5150 and we're left with 635.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6350, and continue the process.

On to step 14:
If we divide 6350 by 645, we get 9 and a remainder of 545.
Write down 9 as next digit of the result. 
Result so far: 139364.519379
If we take 5805 away from 6350, we end up with 545.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5450, and continue the process.

Let's proceed to step 15:
When dividing 5450 by 645, we get 8 with a remainder of 290.
Put 8 as the next digit of the answer. 
Result so far: 139364.5193798
Deduct 5160 from 5450 and we're left with 290.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2900, and continue the process.

On to step 16:
645 can be fit into 2900 4 times, resulting in a remainder of 320.
Use 4 as the next digit of our solution. 
Result so far: 139364.51937984
The remainder is 320 after subtracting 2580 from 2900.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3200, and continue the process.

The final outcome is 139364.51937984, with a leftover of 3.2e-07.