We look at the division of 87042820 by 660 
The aim is to understand the frequency of 660 in 87042820.

On to step 1:
The number 660 fits into 8 0 times, leaving a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 8, we get 8.
Include the next digit (7) from the dividend after 8, then repeat: 87 / 660

Let's proceed to step 2:
660 can be fit into 87 0 times, resulting in a remainder of 87.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 87 leaves us with 87.
Grab the next digit (0) from the dividend, add it to 87, then carry on: 870 / 660

Going ahead to step 3:
660 goes into 870 1 times with a remainder of 210.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
If we subtract 660 from 870, we get 210.
Include the next digit (4) from the dividend after 210, then repeat: 2104 / 660

Moving on to step 4:
660 can be fit into 2104 3 times, resulting in a remainder of 124.
The number 3 becomes the next digit in our result. 
Result so far: 13.0
Deduct 1980 from 2104 and we're left with 124.
Append the next digit (2) from the dividend to 124 and continue with: 1242 / 660

On to step 5:
If we divide 1242 by 660, we get 1 and a remainder of 582.
Use 1 as the next digit of our solution. 
Result so far: 131.0
Subtract 660 from 1242 to get 582.
Append the next digit (8) from the dividend to 582 and continue with: 5828 / 660

Going ahead to step 6:
660 goes into 5828 8 times with a remainder of 548.
The next digit of our result is 8. 
Result so far: 1318.0
Subtracting 5280 from 5828 leaves us with 548.
Include the next digit (2) from the dividend after 548, then repeat: 5482 / 660

Going ahead to step 7:
660 goes into 5482 8 times with a remainder of 202.
Write down 8 as next digit of the result. 
Result so far: 13188.0
If we subtract 5280 from 5482, we get 202.
Append the next digit (0) from the dividend to 202 and continue with: 2020 / 660

Going ahead to step 8:
When dividing 2020 by 660, we get 3 with a remainder of 40.
The number 3 becomes the next digit in our result. 
Result so far: 131883.0
If we subtract 1980 from 2020, 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.

Moving on to step 9:
400 divided by 660 is 0 with a remainder of 400.
The next digit of our result is 0. 
Result so far: 131883.0
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.

Step 10:
The number 660 fits into 4000 6 times, leaving a remainder of 40.
The number 6 becomes the next digit in our result. 
Result so far: 131883.06
Subtract 3960 from 4000 to 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.

On to step 11:
660 goes into 400 0 times with a remainder of 400.
The number 0 becomes the next digit in our result. 
Result so far: 131883.06
If we take 0 away from 400, we end up 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.

On to step 12:
If we divide 4000 by 660, we get 6 and a remainder of 40.
The number 6 becomes the next digit in our result. 
Result so far: 131883.0606
If we subtract 3960 from 4000, 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.

Step 13:
660 can be fit into 400 0 times, resulting in a remainder of 400.
Record the quotient 0 as the next digit in the result. 
Result so far: 131883.0606
Subtract 0 from 400 to get 400.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4000, and continue the process.

Step 14:
660 can be fit into 4000 6 times, resulting in a remainder of 40.
Record the quotient 6 as the next digit in the result. 
Result so far: 131883.060606
Deduct 3960 from 4000 and we're left with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Step 15:
660 can be fit into 400 0 times, resulting in a remainder of 400.
The number 0 becomes the next digit in our result. 
Result so far: 131883.060606
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.

Advancing to step 16:
If we divide 4000 by 660, we get 6 and a remainder of 40.
The next digit of our result is 6. 
Result so far: 131883.06060606
Deduct 3960 from 4000 and we're left with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

The final result is 131883.06060606 with a remainder of 4e-08.