We look at the division of 66245255 by 378 
The aim is to understand the frequency of 378 in 66245255.

Let's proceed to step 1:
The number 378 fits into 6 0 times, leaving a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Append the next digit (6) from the dividend to 6 and continue with: 66 / 378

Let's proceed to step 2:
If we divide 66 by 378, we get 0 and a remainder of 66.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 66 leaves us with 66.
Grab the next digit (2) from the dividend, add it to 66, then carry on: 662 / 378

Let's proceed to step 3:
378 can be fit into 662 1 times, resulting in a remainder of 284.
Write down 1 as next digit of the result. 
Result so far: 1.0
If we subtract 378 from 662, we get 284.
Take the next digit (4) from the dividend and append it to 284, then repeat: 2844 / 378

Step 4:
378 goes into 2844 7 times with a remainder of 198.
The number 7 becomes the next digit in our result. 
Result so far: 17.0
Deduct 2646 from 2844 and we're left with 198.
Bring next digit (5) of the dividend behind the 198 and repeat the process: 1985 / 378

Step 5:
If we divide 1985 by 378, we get 5 and a remainder of 95.
The next digit of our result is 5. 
Result so far: 175.0
If we take 1890 away from 1985, we end up with 95.
Append the next digit (2) from the dividend to 95 and continue with: 952 / 378

On to step 6:
If we divide 952 by 378, we get 2 and a remainder of 196.
Write down 2 as next digit of the result. 
Result so far: 1752.0
Deduct 756 from 952 and we're left with 196.
Fetch the next digit (5) from the dividend, attach it to 196 and continue: 1965 / 378

Moving on to step 7:
1965 divided by 378 is 5 with a remainder of 75.
The number 5 becomes the next digit in our result. 
Result so far: 17525.0
If we take 1890 away from 1965, we end up with 75.
Include the next digit (5) from the dividend after 75, then repeat: 755 / 378

On to step 8:
378 goes into 755 1 times with a remainder of 377.
The next digit of our result is 1. 
Result so far: 175251.0
Deduct 378 from 755 and we're left with 377.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3770, and continue the process.

Step 9:
378 can be fit into 3770 9 times, resulting in a remainder of 368.
The next digit of our result is 9. 
Result so far: 175251.9
If we take 3402 away from 3770, we end up with 368.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3680, and continue the process.

On to step 10:
If we divide 3680 by 378, we get 9 and a remainder of 278.
The next digit of our result is 9. 
Result so far: 175251.99
If we subtract 3402 from 3680, we get 278.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2780, and continue the process.

The final result is 175251.99 with a remainder of 0.278.