21318842 ÷ 521 
The aim is to understand the frequency of 521 in 21318842.

Advancing to step 1:
When dividing 2 by 521, we get 0 with a remainder of 2.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 2 and we're left with 2.
Include the next digit (1) from the dividend after 2, then repeat: 21 / 521

Going ahead to step 2:
521 can be fit into 21 0 times, resulting in a remainder of 21.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 21, we end up with 21.
Bring next digit (3) of the dividend behind the 21 and repeat the process: 213 / 521

Let's proceed to step 3:
521 can be fit into 213 0 times, resulting in a remainder of 213.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 213 to get 213.
Fetch the next digit (1) from the dividend, attach it to 213 and continue: 2131 / 521

Moving on to step 4:
521 goes into 2131 4 times with a remainder of 47.
Put 4 as the next digit of the answer. 
Result so far: 4.0
The remainder is 47 after subtracting 2084 from 2131.
Fetch the next digit (8) from the dividend, attach it to 47 and continue: 478 / 521

Going ahead to step 5:
If we divide 478 by 521, we get 0 and a remainder of 478.
Use 0 as the next digit of our solution. 
Result so far: 40.0
Subtracting 0 from 478 leaves us with 478.
Include the next digit (8) from the dividend after 478, then repeat: 4788 / 521

Advancing to step 6:
521 can be fit into 4788 9 times, resulting in a remainder of 99.
The number 9 becomes the next digit in our result. 
Result so far: 409.0
Subtracting 4689 from 4788 leaves us with 99.
Take the next digit (4) from the dividend and append it to 99, then repeat: 994 / 521

Let's proceed to step 7:
When dividing 994 by 521, we get 1 with a remainder of 473.
Put 1 as the next digit of the answer. 
Result so far: 4091.0
Subtract 521 from 994 to get 473.
Take the next digit (2) from the dividend and append it to 473, then repeat: 4732 / 521

Let's proceed to step 8:
521 can be fit into 4732 9 times, resulting in a remainder of 43.
The number 9 becomes the next digit in our result. 
Result so far: 40919.0
Subtracting 4689 from 4732 leaves us with 43.
Since there are no more digits in the dividend, we add a zero to the remainder making it 430, and continue the process.

On to step 9:
521 can be fit into 430 0 times, resulting in a remainder of 430.
Write down 0 as next digit of the result. 
Result so far: 40919.0
Deduct 0 from 430 and we're left with 430.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4300, and continue the process.

Advancing to step 10:
4300 divided by 521 is 8 with a remainder of 132.
Use 8 as the next digit of our solution. 
Result so far: 40919.08
If we take 4168 away from 4300, we end up with 132.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1320, and continue the process.

Moving on to step 11:
521 goes into 1320 2 times with a remainder of 278.
Write down 2 as next digit of the result. 
Result so far: 40919.082
Subtract 1042 from 1320 to 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.

Let's proceed to step 12:
The number 521 fits into 2780 5 times, leaving a remainder of 175.
Put 5 as the next digit of the answer. 
Result so far: 40919.0825
The remainder is 175 after subtracting 2605 from 2780.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1750, and continue the process.

Going ahead to step 13:
The number 521 fits into 1750 3 times, leaving a remainder of 187.
Record the quotient 3 as the next digit in the result. 
Result so far: 40919.08253
Subtracting 1563 from 1750 leaves us with 187.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1870, and continue the process.

Advancing to step 14:
The number 521 fits into 1870 3 times, leaving a remainder of 307.
Use 3 as the next digit of our solution. 
Result so far: 40919.082533
Subtracting 1563 from 1870 leaves us with 307.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3070, and continue the process.

After the division, we end up with 40919.082533 and a remainder of 3.07e-05.