We look at the division of 915466 by 21 
The aim is to understand the frequency of 21 in 915466.

Let's proceed to step 1:
The number 21 fits into 9 0 times, leaving a remainder of 9.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 9 and we're left with 9.
Grab the next digit (1) from the dividend, add it to 9, then carry on: 91 / 21

Step 2:
91 divided by 21 is 4 with a remainder of 7.
Put 4 as the next digit of the answer. 
Result so far: 4.0
Subtract 84 from 91 to get 7.
Include the next digit (5) from the dividend after 7, then repeat: 75 / 21

On to step 3:
If we divide 75 by 21, we get 3 and a remainder of 12.
The number 3 becomes the next digit in our result. 
Result so far: 43.0
Subtract 63 from 75 to get 12.
Append the next digit (4) from the dividend to 12 and continue with: 124 / 21

On to step 4:
21 goes into 124 5 times with a remainder of 19.
The next digit of our result is 5. 
Result so far: 435.0
The remainder is 19 after subtracting 105 from 124.
Take the next digit (6) from the dividend and append it to 19, then repeat: 196 / 21

Let's proceed to step 5:
If we divide 196 by 21, we get 9 and a remainder of 7.
The number 9 becomes the next digit in our result. 
Result so far: 4359.0
If we subtract 189 from 196, we get 7.
Take the next digit (6) from the dividend and append it to 7, then repeat: 76 / 21

Advancing to step 6:
The number 21 fits into 76 3 times, leaving a remainder of 13.
Use 3 as the next digit of our solution. 
Result so far: 43593.0
Deduct 63 from 76 and we're left with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Going ahead to step 7:
The number 21 fits into 130 6 times, leaving a remainder of 4.
The next digit of our result is 6. 
Result so far: 43593.6
If we take 126 away from 130, we end up with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Advancing to step 8:
If we divide 40 by 21, we get 1 and a remainder of 19.
Use 1 as the next digit of our solution. 
Result so far: 43593.61
If we subtract 21 from 40, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Let's proceed to step 9:
If we divide 190 by 21, we get 9 and a remainder of 1.
Put 9 as the next digit of the answer. 
Result so far: 43593.619
If we take 189 away from 190, we end up with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Moving on to step 10:
21 can be fit into 10 0 times, resulting in a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 43593.619
Subtracting 0 from 10 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Let's proceed to step 11:
When dividing 100 by 21, we get 4 with a remainder of 16.
Use 4 as the next digit of our solution. 
Result so far: 43593.61904
If we take 84 away from 100, we end up with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

On to step 12:
21 can be fit into 160 7 times, resulting in a remainder of 13.
Record the quotient 7 as the next digit in the result. 
Result so far: 43593.619047
Deduct 147 from 160 and we're left with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

On to step 13:
The number 21 fits into 130 6 times, leaving a remainder of 4.
Write down 6 as next digit of the result. 
Result so far: 43593.6190476
Subtracting 126 from 130 leaves us with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Advancing to step 14:
When dividing 40 by 21, we get 1 with a remainder of 19.
Put 1 as the next digit of the answer. 
Result so far: 43593.61904761
Deduct 21 from 40 and we're left with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

The quotient of the division is 43593.61904761, and the remainder is 1.9e-08.