66103451 divided by 129 
The aim is to understand the frequency of 129 in 66103451.

Let's proceed to step 1:
The number 129 fits into 6 0 times, leaving a remainder of 6.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Grab the next digit (6) from the dividend, add it to 6, then carry on: 66 / 129

Going ahead to step 2:
If we divide 66 by 129, we get 0 and a remainder of 66.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 66, we get 66.
Append the next digit (1) from the dividend to 66 and continue with: 661 / 129

Let's proceed to step 3:
The number 129 fits into 661 5 times, leaving a remainder of 16.
Record the quotient 5 as the next digit in the result. 
Result so far: 5.0
The remainder is 16 after subtracting 645 from 661.
Grab the next digit (0) from the dividend, add it to 16, then carry on: 160 / 129

Step 4:
When dividing 160 by 129, we get 1 with a remainder of 31.
The number 1 becomes the next digit in our result. 
Result so far: 51.0
Subtract 129 from 160 to get 31.
Take the next digit (3) from the dividend and append it to 31, then repeat: 313 / 129

Step 5:
129 can be fit into 313 2 times, resulting in a remainder of 55.
Use 2 as the next digit of our solution. 
Result so far: 512.0
Subtract 258 from 313 to get 55.
Include the next digit (4) from the dividend after 55, then repeat: 554 / 129

Moving on to step 6:
If we divide 554 by 129, we get 4 and a remainder of 38.
Write down 4 as next digit of the result. 
Result so far: 5124.0
Subtracting 516 from 554 leaves us with 38.
Fetch the next digit (5) from the dividend, attach it to 38 and continue: 385 / 129

Step 7:
385 divided by 129 is 2 with a remainder of 127.
The number 2 becomes the next digit in our result. 
Result so far: 51242.0
If we subtract 258 from 385, we get 127.
Grab the next digit (1) from the dividend, add it to 127, then carry on: 1271 / 129

On to step 8:
When dividing 1271 by 129, we get 9 with a remainder of 110.
Put 9 as the next digit of the answer. 
Result so far: 512429.0
Subtracting 1161 from 1271 leaves us with 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1100, and continue the process.

Advancing to step 9:
129 can be fit into 1100 8 times, resulting in a remainder of 68.
Use 8 as the next digit of our solution. 
Result so far: 512429.8
If we subtract 1032 from 1100, we get 68.
Since there are no more digits in the dividend, we add a zero to the remainder making it 680, and continue the process.

Moving on to step 10:
When dividing 680 by 129, we get 5 with a remainder of 35.
Record the quotient 5 as the next digit in the result. 
Result so far: 512429.85
Subtracting 645 from 680 leaves us with 35.
Since there are no more digits in the dividend, we add a zero to the remainder making it 350, and continue the process.

Moving on to step 11:
If we divide 350 by 129, we get 2 and a remainder of 92.
Write down 2 as next digit of the result. 
Result so far: 512429.852
Subtract 258 from 350 to get 92.
Since there are no more digits in the dividend, we add a zero to the remainder making it 920, and continue the process.

Moving on to step 12:
129 goes into 920 7 times with a remainder of 17.
The next digit of our result is 7. 
Result so far: 512429.8527
Subtracting 903 from 920 leaves us with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Moving on to step 13:
129 goes into 170 1 times with a remainder of 41.
Record the quotient 1 as the next digit in the result. 
Result so far: 512429.85271
The remainder is 41 after subtracting 129 from 170.
Since there are no more digits in the dividend, we add a zero to the remainder making it 410, and continue the process.

On to step 14:
If we divide 410 by 129, we get 3 and a remainder of 23.
Write down 3 as next digit of the result. 
Result so far: 512429.852713
Subtracting 387 from 410 leaves us with 23.
Since there are no more digits in the dividend, we add a zero to the remainder making it 230, and continue the process.

Step 15:
The number 129 fits into 230 1 times, leaving a remainder of 101.
Record the quotient 1 as the next digit in the result. 
Result so far: 512429.8527131
Subtracting 129 from 230 leaves us with 101.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1010, and continue the process.

Advancing to step 16:
The number 129 fits into 1010 7 times, leaving a remainder of 107.
Write down 7 as next digit of the result. 
Result so far: 512429.85271317
If we subtract 903 from 1010, we get 107.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1070, and continue the process.

The final result is 512429.85271317 with a remainder of 1.07e-07.