We look at the division of 49428008 by 521 
The aim is to understand the frequency of 521 in 49428008.

Going ahead to step 1:
If we divide 4 by 521, we get 0 and a remainder of 4.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 4, we end up with 4.
Include the next digit (9) from the dividend after 4, then repeat: 49 / 521

Advancing to step 2:
49 divided by 521 is 0 with a remainder of 49.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 49 and we're left with 49.
Fetch the next digit (4) from the dividend, attach it to 49 and continue: 494 / 521

On to step 3:
When dividing 494 by 521, we get 0 with a remainder of 494.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 494, we end up with 494.
Grab the next digit (2) from the dividend, add it to 494, then carry on: 4942 / 521

Going ahead to step 4:
When dividing 4942 by 521, we get 9 with a remainder of 253.
Use 9 as the next digit of our solution. 
Result so far: 9.0
Subtracting 4689 from 4942 leaves us with 253.
Append the next digit (8) from the dividend to 253 and continue with: 2538 / 521

Moving on to step 5:
The number 521 fits into 2538 4 times, leaving a remainder of 454.
Put 4 as the next digit of the answer. 
Result so far: 94.0
If we take 2084 away from 2538, we end up with 454.
Take the next digit (0) from the dividend and append it to 454, then repeat: 4540 / 521

Going ahead to step 6:
4540 divided by 521 is 8 with a remainder of 372.
Write down 8 as next digit of the result. 
Result so far: 948.0
Subtract 4168 from 4540 to get 372.
Grab the next digit (0) from the dividend, add it to 372, then carry on: 3720 / 521

Step 7:
3720 divided by 521 is 7 with a remainder of 73.
Use 7 as the next digit of our solution. 
Result so far: 9487.0
Subtract 3647 from 3720 to get 73.
Bring next digit (8) of the dividend behind the 73 and repeat the process: 738 / 521

Moving on to step 8:
521 goes into 738 1 times with a remainder of 217.
Use 1 as the next digit of our solution. 
Result so far: 94871.0
If we subtract 521 from 738, we get 217.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2170, and continue the process.

Moving on to step 9:
The number 521 fits into 2170 4 times, leaving a remainder of 86.
Use 4 as the next digit of our solution. 
Result so far: 94871.4
The remainder is 86 after subtracting 2084 from 2170.
Since there are no more digits in the dividend, we add a zero to the remainder making it 860, and continue the process.

Going ahead to step 10:
If we divide 860 by 521, we get 1 and a remainder of 339.
Use 1 as the next digit of our solution. 
Result so far: 94871.41
If we take 521 away from 860, we end up with 339.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3390, and continue the process.

Going ahead to step 11:
521 goes into 3390 6 times with a remainder of 264.
Write down 6 as next digit of the result. 
Result so far: 94871.416
If we subtract 3126 from 3390, we get 264.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2640, and continue the process.

Going ahead to step 12:
When dividing 2640 by 521, we get 5 with a remainder of 35.
The number 5 becomes the next digit in our result. 
Result so far: 94871.4165
The remainder is 35 after subtracting 2605 from 2640.
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 13:
521 goes into 350 0 times with a remainder of 350.
The next digit of our result is 0. 
Result so far: 94871.4165
Deduct 0 from 350 and we're left with 350.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3500, and continue the process.

On to step 14:
521 goes into 3500 6 times with a remainder of 374.
Write down 6 as next digit of the result. 
Result so far: 94871.416506
If we subtract 3126 from 3500, we get 374.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3740, and continue the process.

Step 15:
521 can be fit into 3740 7 times, resulting in a remainder of 93.
Use 7 as the next digit of our solution. 
Result so far: 94871.4165067
If we subtract 3647 from 3740, we get 93.
Since there are no more digits in the dividend, we add a zero to the remainder making it 930, and continue the process.

Going ahead to step 16:
When dividing 930 by 521, we get 1 with a remainder of 409.
Record the quotient 1 as the next digit in the result. 
Result so far: 94871.41650671
Subtract 521 from 930 to get 409.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4090, and continue the process.

After the division, we end up with 94871.41650671 and a remainder of 4.09e-07.