We divide 78376661 by 521
The aim is to understand the frequency of 521 in 78376661.

Step 1:
521 goes into 7 0 times with a remainder of 7.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 7 to get 7.
Grab the next digit (8) from the dividend, add it to 7, then carry on: 78 / 521

Going ahead to step 2:
If we divide 78 by 521, we get 0 and a remainder of 78.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 78, we end up with 78.
Include the next digit (3) from the dividend after 78, then repeat: 783 / 521

On to step 3:
521 goes into 783 1 times with a remainder of 262.
Put 1 as the next digit of the answer. 
Result so far: 1.0
Subtracting 521 from 783 leaves us with 262.
Bring next digit (7) of the dividend behind the 262 and repeat the process: 2627 / 521

Moving on to step 4:
The number 521 fits into 2627 5 times, leaving a remainder of 22.
Record the quotient 5 as the next digit in the result. 
Result so far: 15.0
The remainder is 22 after subtracting 2605 from 2627.
Include the next digit (6) from the dividend after 22, then repeat: 226 / 521

Moving on to step 5:
If we divide 226 by 521, we get 0 and a remainder of 226.
Use 0 as the next digit of our solution. 
Result so far: 150.0
If we take 0 away from 226, we end up with 226.
Take the next digit (6) from the dividend and append it to 226, then repeat: 2266 / 521

Going ahead to step 6:
The number 521 fits into 2266 4 times, leaving a remainder of 182.
The number 4 becomes the next digit in our result. 
Result so far: 1504.0
Subtract 2084 from 2266 to get 182.
Bring next digit (6) of the dividend behind the 182 and repeat the process: 1826 / 521

Step 7:
The number 521 fits into 1826 3 times, leaving a remainder of 263.
The number 3 becomes the next digit in our result. 
Result so far: 15043.0
The remainder is 263 after subtracting 1563 from 1826.
Take the next digit (1) from the dividend and append it to 263, then repeat: 2631 / 521

On to step 8:
When dividing 2631 by 521, we get 5 with a remainder of 26.
Use 5 as the next digit of our solution. 
Result so far: 150435.0
If we take 2605 away from 2631, we end up with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

Step 9:
260 divided by 521 is 0 with a remainder of 260.
Record the quotient 0 as the next digit in the result. 
Result so far: 150435.0
If we subtract 0 from 260, we get 260.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2600, and continue the process.

Advancing to step 10:
521 can be fit into 2600 4 times, resulting in a remainder of 516.
The number 4 becomes the next digit in our result. 
Result so far: 150435.04
If we take 2084 away from 2600, we end up with 516.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5160, and continue the process.

Advancing to step 11:
521 can be fit into 5160 9 times, resulting in a remainder of 471.
Record the quotient 9 as the next digit in the result. 
Result so far: 150435.049
If we take 4689 away from 5160, we end up with 471.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4710, and continue the process.

Step 12:
If we divide 4710 by 521, we get 9 and a remainder of 21.
Put 9 as the next digit of the answer. 
Result so far: 150435.0499
Deduct 4689 from 4710 and we're left with 21.
Since there are no more digits in the dividend, we add a zero to the remainder making it 210, and continue the process.

After the division, we end up with 150435.0499 and a remainder of 0.00021.