We look at the division of 659971 by 66 
The aim is to understand the frequency of 66 in 659971.

Going ahead to step 1:
66 goes into 6 0 times with a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Bring next digit (5) of the dividend behind the 6 and repeat the process: 65 / 66

Going ahead to step 2:
66 can be fit into 65 0 times, resulting in a remainder of 65.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 65 after subtracting 0 from 65.
Fetch the next digit (9) from the dividend, attach it to 65 and continue: 659 / 66

On to step 3:
If we divide 659 by 66, we get 9 and a remainder of 65.
Write down 9 as next digit of the result. 
Result so far: 9.0
If we subtract 594 from 659, we get 65.
Append the next digit (9) from the dividend to 65 and continue with: 659 / 66

Going ahead to step 4:
66 goes into 659 9 times with a remainder of 65.
The next digit of our result is 9. 
Result so far: 99.0
Subtracting 594 from 659 leaves us with 65.
Fetch the next digit (7) from the dividend, attach it to 65 and continue: 657 / 66

On to step 5:
657 divided by 66 is 9 with a remainder of 63.
Put 9 as the next digit of the answer. 
Result so far: 999.0
Subtract 594 from 657 to get 63.
Append the next digit (1) from the dividend to 63 and continue with: 631 / 66

Moving on to step 6:
If we divide 631 by 66, we get 9 and a remainder of 37.
Write down 9 as next digit of the result. 
Result so far: 9999.0
If we take 594 away from 631, we end up with 37.
Since there are no more digits in the dividend, we add a zero to the remainder making it 370, and continue the process.

On to step 7:
66 can be fit into 370 5 times, resulting in a remainder of 40.
Put 5 as the next digit of the answer. 
Result so far: 9999.5
If we subtract 330 from 370, 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.

Going ahead to step 8:
When dividing 400 by 66, we get 6 with a remainder of 4.
Record the quotient 6 as the next digit in the result. 
Result so far: 9999.56
Subtracting 396 from 400 leaves us with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Moving on to step 9:
66 goes into 40 0 times with a remainder of 40.
The next digit of our result is 0. 
Result so far: 9999.56
Subtract 0 from 40 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 10:
The number 66 fits into 400 6 times, leaving a remainder of 4.
The number 6 becomes the next digit in our result. 
Result so far: 9999.5606
The remainder is 4 after subtracting 396 from 400.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Going ahead to step 11:
If we divide 40 by 66, we get 0 and a remainder of 40.
Write down 0 as next digit of the result. 
Result so far: 9999.5606
Deduct 0 from 40 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 12:
The number 66 fits into 400 6 times, leaving a remainder of 4.
Use 6 as the next digit of our solution. 
Result so far: 9999.560606
Subtracting 396 from 400 leaves us with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Advancing to step 13:
When dividing 40 by 66, we get 0 with a remainder of 40.
Put 0 as the next digit of the answer. 
Result so far: 9999.560606
The remainder is 40 after subtracting 0 from 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 14:
If we divide 400 by 66, we get 6 and a remainder of 4.
Put 6 as the next digit of the answer. 
Result so far: 9999.56060606
If we take 396 away from 400, we end up with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

In conclusion, the division gives 9999.56060606 with a balance of 4e-09.