We're dividing 21437209 by 19 
The aim is to understand the frequency of 19 in 21437209.

Step 1:
The number 19 fits into 2 0 times, leaving 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 / 19

Going ahead to step 2:
If we divide 21 by 19, we get 1 and a remainder of 2.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Subtracting 19 from 21 leaves us with 2.
Fetch the next digit (4) from the dividend, attach it to 2 and continue: 24 / 19

Let's proceed to step 3:
When dividing 24 by 19, we get 1 with a remainder of 5.
Put 1 as the next digit of the answer. 
Result so far: 11.0
Subtract 19 from 24 to get 5.
Bring next digit (3) of the dividend behind the 5 and repeat the process: 53 / 19

Moving on to step 4:
53 divided by 19 is 2 with a remainder of 15.
Put 2 as the next digit of the answer. 
Result so far: 112.0
The remainder is 15 after subtracting 38 from 53.
Grab the next digit (7) from the dividend, add it to 15, then carry on: 157 / 19

Going ahead to step 5:
19 goes into 157 8 times with a remainder of 5.
The next digit of our result is 8. 
Result so far: 1128.0
Subtract 152 from 157 to get 5.
Take the next digit (2) from the dividend and append it to 5, then repeat: 52 / 19

Let's proceed to step 6:
19 can be fit into 52 2 times, resulting in a remainder of 14.
Record the quotient 2 as the next digit in the result. 
Result so far: 11282.0
If we subtract 38 from 52, we get 14.
Fetch the next digit (0) from the dividend, attach it to 14 and continue: 140 / 19

On to step 7:
19 goes into 140 7 times with a remainder of 7.
Put 7 as the next digit of the answer. 
Result so far: 112827.0
Subtract 133 from 140 to get 7.
Take the next digit (9) from the dividend and append it to 7, then repeat: 79 / 19

Moving on to step 8:
19 goes into 79 4 times with a remainder of 3.
The next digit of our result is 4. 
Result so far: 1128274.0
The remainder is 3 after subtracting 76 from 79.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Going ahead to step 9:
19 can be fit into 30 1 times, resulting in a remainder of 11.
The next digit of our result is 1. 
Result so far: 1128274.1
The remainder is 11 after subtracting 19 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

On to step 10:
19 goes into 110 5 times with a remainder of 15.
Put 5 as the next digit of the answer. 
Result so far: 1128274.15
If we subtract 95 from 110, we get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Step 11:
19 can be fit into 150 7 times, resulting in a remainder of 17.
The number 7 becomes the next digit in our result. 
Result so far: 1128274.157
Subtracting 133 from 150 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.

On to step 12:
170 divided by 19 is 8 with a remainder of 18.
The next digit of our result is 8. 
Result so far: 1128274.1578
If we subtract 152 from 170, we get 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Moving on to step 13:
When dividing 180 by 19, we get 9 with a remainder of 9.
Put 9 as the next digit of the answer. 
Result so far: 1128274.15789
If we subtract 171 from 180, we get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Moving on to step 14:
19 can be fit into 90 4 times, resulting in a remainder of 14.
Write down 4 as next digit of the result. 
Result so far: 1128274.157894
The remainder is 14 after subtracting 76 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Going ahead to step 15:
140 divided by 19 is 7 with a remainder of 7.
Write down 7 as next digit of the result. 
Result so far: 1128274.1578947
The remainder is 7 after subtracting 133 from 140.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

On to step 16:
70 divided by 19 is 3 with a remainder of 13.
The number 3 becomes the next digit in our result. 
Result so far: 1128274.15789473
If we take 57 away from 70, we end up 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.

The final outcome is 1128274.15789473, with a leftover of 1.3e-08.