53391456 divided by 666 
The aim is to understand the frequency of 666 in 53391456.

Advancing to step 1:
666 can be fit into 5 0 times, resulting in a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 5 and we're left with 5.
Append the next digit (3) from the dividend to 5 and continue with: 53 / 666

Moving on to step 2:
If we divide 53 by 666, we get 0 and a remainder of 53.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 53 and we're left with 53.
Bring next digit (3) of the dividend behind the 53 and repeat the process: 533 / 666

On to step 3:
If we divide 533 by 666, we get 0 and a remainder of 533.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 533 leaves us with 533.
Bring next digit (9) of the dividend behind the 533 and repeat the process: 5339 / 666

Moving on to step 4:
When dividing 5339 by 666, we get 8 with a remainder of 11.
Put 8 as the next digit of the answer. 
Result so far: 8.0
If we take 5328 away from 5339, we end up with 11.
Take the next digit (1) from the dividend and append it to 11, then repeat: 111 / 666

Moving on to step 5:
111 divided by 666 is 0 with a remainder of 111.
Write down 0 as next digit of the result. 
Result so far: 80.0
If we subtract 0 from 111, we get 111.
Bring next digit (4) of the dividend behind the 111 and repeat the process: 1114 / 666

Step 6:
The number 666 fits into 1114 1 times, leaving a remainder of 448.
Put 1 as the next digit of the answer. 
Result so far: 801.0
Deduct 666 from 1114 and we're left with 448.
Bring next digit (5) of the dividend behind the 448 and repeat the process: 4485 / 666

On to step 7:
The number 666 fits into 4485 6 times, leaving a remainder of 489.
Write down 6 as next digit of the result. 
Result so far: 8016.0
Subtracting 3996 from 4485 leaves us with 489.
Take the next digit (6) from the dividend and append it to 489, then repeat: 4896 / 666

Step 8:
The number 666 fits into 4896 7 times, leaving a remainder of 234.
Put 7 as the next digit of the answer. 
Result so far: 80167.0
The remainder is 234 after subtracting 4662 from 4896.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2340, and continue the process.

Advancing to step 9:
If we divide 2340 by 666, we get 3 and a remainder of 342.
Record the quotient 3 as the next digit in the result. 
Result so far: 80167.3
If we take 1998 away from 2340, we end up with 342.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3420, and continue the process.

Moving on to step 10:
The number 666 fits into 3420 5 times, leaving a remainder of 90.
Use 5 as the next digit of our solution. 
Result so far: 80167.35
If we take 3330 away from 3420, we end up with 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 900, and continue the process.

Going ahead to step 11:
666 goes into 900 1 times with a remainder of 234.
Write down 1 as next digit of the result. 
Result so far: 80167.351
Subtracting 666 from 900 leaves us with 234.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2340, and continue the process.

Step 12:
666 goes into 2340 3 times with a remainder of 342.
Record the quotient 3 as the next digit in the result. 
Result so far: 80167.3513
The remainder is 342 after subtracting 1998 from 2340.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3420, and continue the process.

Step 13:
3420 divided by 666 is 5 with a remainder of 90.
Write down 5 as next digit of the result. 
Result so far: 80167.35135
If we subtract 3330 from 3420, we get 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 900, and continue the process.

On to step 14:
666 goes into 900 1 times with a remainder of 234.
Write down 1 as next digit of the result. 
Result so far: 80167.351351
Deduct 666 from 900 and we're left with 234.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2340, and continue the process.

Going ahead to step 15:
The number 666 fits into 2340 3 times, leaving a remainder of 342.
The number 3 becomes the next digit in our result. 
Result so far: 80167.3513513
If we take 1998 away from 2340, we end up with 342.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3420, and continue the process.

Going ahead to step 16:
When dividing 3420 by 666, we get 5 with a remainder of 90.
The next digit of our result is 5. 
Result so far: 80167.35135135
The remainder is 90 after subtracting 3330 from 3420.
Since there are no more digits in the dividend, we add a zero to the remainder making it 900, and continue the process.

The final outcome is 80167.35135135, with a leftover of 9e-08.