19217495 divided by 21 
The aim is to understand the frequency of 21 in 19217495.

On to step 1:
21 can be fit into 1 0 times, resulting in a remainder of 1.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Include the next digit (9) from the dividend after 1, then repeat: 19 / 21

Step 2:
When dividing 19 by 21, we get 0 with a remainder of 19.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 19 after subtracting 0 from 19.
Bring next digit (2) of the dividend behind the 19 and repeat the process: 192 / 21

Moving on to step 3:
The number 21 fits into 192 9 times, leaving a remainder of 3.
Record the quotient 9 as the next digit in the result. 
Result so far: 9.0
If we subtract 189 from 192, we get 3.
Fetch the next digit (1) from the dividend, attach it to 3 and continue: 31 / 21

On to step 4:
When dividing 31 by 21, we get 1 with a remainder of 10.
Write down 1 as next digit of the result. 
Result so far: 91.0
Subtract 21 from 31 to get 10.
Append the next digit (7) from the dividend to 10 and continue with: 107 / 21

Going ahead to step 5:
If we divide 107 by 21, we get 5 and a remainder of 2.
Record the quotient 5 as the next digit in the result. 
Result so far: 915.0
Deduct 105 from 107 and we're left with 2.
Include the next digit (4) from the dividend after 2, then repeat: 24 / 21

Going ahead to step 6:
If we divide 24 by 21, we get 1 and a remainder of 3.
Record the quotient 1 as the next digit in the result. 
Result so far: 9151.0
Deduct 21 from 24 and we're left with 3.
Take the next digit (9) from the dividend and append it to 3, then repeat: 39 / 21

On to step 7:
21 goes into 39 1 times with a remainder of 18.
The number 1 becomes the next digit in our result. 
Result so far: 91511.0
The remainder is 18 after subtracting 21 from 39.
Grab the next digit (5) from the dividend, add it to 18, then carry on: 185 / 21

Advancing to step 8:
21 goes into 185 8 times with a remainder of 17.
Use 8 as the next digit of our solution. 
Result so far: 915118.0
Subtracting 168 from 185 leaves us with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Going ahead to step 9:
If we divide 170 by 21, we get 8 and a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 915118.8
The remainder is 2 after subtracting 168 from 170.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Let's proceed to step 10:
20 divided by 21 is 0 with a remainder of 20.
Write down 0 as next digit of the result. 
Result so far: 915118.8
Subtracting 0 from 20 leaves us with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Moving on to step 11:
If we divide 200 by 21, we get 9 and a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 915118.809
The remainder is 11 after subtracting 189 from 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Let's proceed to step 12:
If we divide 110 by 21, we get 5 and a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 915118.8095
If we subtract 105 from 110, we get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Let's proceed to step 13:
If we divide 50 by 21, we get 2 and a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 915118.80952
Deduct 42 from 50 and we're left with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Advancing to step 14:
80 divided by 21 is 3 with a remainder of 17.
Write down 3 as next digit of the result. 
Result so far: 915118.809523
The remainder is 17 after subtracting 63 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

On to step 15:
21 can be fit into 170 8 times, resulting in a remainder of 2.
The next digit of our result is 8. 
Result so far: 915118.8095238
Subtract 168 from 170 to get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

On to step 16:
21 goes into 20 0 times with a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 915118.8095238
If we subtract 0 from 20, we get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

The final outcome is 915118.8095238, with a leftover of 2e-08.