21005878 ÷ 19 
The aim is to understand the frequency of 19 in 21005878.

Advancing to step 1:
19 can be fit into 2 0 times, resulting in a remainder of 2.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 2 to get 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 19

Let's proceed to step 2:
The number 19 fits into 21 1 times, leaving a remainder of 2.
The next digit of our result is 1. 
Result so far: 1.0
If we take 19 away from 21, we end up with 2.
Take the next digit (0) from the dividend and append it to 2, then repeat: 20 / 19

Advancing to step 3:
20 divided by 19 is 1 with a remainder of 1.
Use 1 as the next digit of our solution. 
Result so far: 11.0
Subtracting 19 from 20 leaves us with 1.
Take the next digit (0) from the dividend and append it to 1, then repeat: 10 / 19

Moving on to step 4:
19 can be fit into 10 0 times, resulting in a remainder of 10.
The next digit of our result is 0. 
Result so far: 110.0
Deduct 0 from 10 and we're left with 10.
Bring next digit (5) of the dividend behind the 10 and repeat the process: 105 / 19

Advancing to step 5:
When dividing 105 by 19, we get 5 with a remainder of 10.
Use 5 as the next digit of our solution. 
Result so far: 1105.0
The remainder is 10 after subtracting 95 from 105.
Bring next digit (8) of the dividend behind the 10 and repeat the process: 108 / 19

Moving on to step 6:
108 divided by 19 is 5 with a remainder of 13.
The number 5 becomes the next digit in our result. 
Result so far: 11055.0
The remainder is 13 after subtracting 95 from 108.
Include the next digit (7) from the dividend after 13, then repeat: 137 / 19

Let's proceed to step 7:
19 goes into 137 7 times with a remainder of 4.
Record the quotient 7 as the next digit in the result. 
Result so far: 110557.0
If we subtract 133 from 137, we get 4.
Take the next digit (8) from the dividend and append it to 4, then repeat: 48 / 19

Let's proceed to step 8:
19 goes into 48 2 times with a remainder of 10.
Put 2 as the next digit of the answer. 
Result so far: 1105572.0
Deduct 38 from 48 and we're left 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.

Step 9:
The number 19 fits into 100 5 times, leaving a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 1105572.5
Subtract 95 from 100 to 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 10:
When dividing 50 by 19, we get 2 with a remainder of 12.
The number 2 becomes the next digit in our result. 
Result so far: 1105572.52
Deduct 38 from 50 and we're left with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Moving on to step 11:
If we divide 120 by 19, we get 6 and a remainder of 6.
Write down 6 as next digit of the result. 
Result so far: 1105572.526
The remainder is 6 after subtracting 114 from 120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Step 12:
When dividing 60 by 19, we get 3 with a remainder of 3.
Write down 3 as next digit of the result. 
Result so far: 1105572.5263
Subtracting 57 from 60 leaves us with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Let's proceed to step 13:
When dividing 30 by 19, we get 1 with a remainder of 11.
Use 1 as the next digit of our solution. 
Result so far: 1105572.52631
Subtract 19 from 30 to get 11.
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 14:
When dividing 110 by 19, we get 5 with a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 1105572.526315
Deduct 95 from 110 and we're left with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

On to step 15:
The number 19 fits into 150 7 times, leaving a remainder of 17.
Use 7 as the next digit of our solution. 
Result so far: 1105572.5263157
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.

Going ahead to step 16:
The number 19 fits into 170 8 times, leaving a remainder of 18.
The number 8 becomes the next digit in our result. 
Result so far: 1105572.52631578
Subtract 152 from 170 to 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.

The final outcome is 1105572.52631578, with a leftover of 1.8e-08.