We look at the division of 378809 by 20 
The aim is to understand the frequency of 20 in 378809.

On to step 1:
3 divided by 20 is 0 with a remainder of 3.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 3 leaves us with 3.
Bring next digit (7) of the dividend behind the 3 and repeat the process: 37 / 20

Going ahead to step 2:
When dividing 37 by 20, we get 1 with a remainder of 17.
Write down 1 as next digit of the result. 
Result so far: 1.0
If we subtract 20 from 37, we get 17.
Include the next digit (8) from the dividend after 17, then repeat: 178 / 20

Going ahead to step 3:
20 goes into 178 8 times with a remainder of 18.
Put 8 as the next digit of the answer. 
Result so far: 18.0
Subtracting 160 from 178 leaves us with 18.
Append the next digit (8) from the dividend to 18 and continue with: 188 / 20

Advancing to step 4:
If we divide 188 by 20, we get 9 and a remainder of 8.
Use 9 as the next digit of our solution. 
Result so far: 189.0
If we take 180 away from 188, we end up with 8.
Take the next digit (0) from the dividend and append it to 8, then repeat: 80 / 20

On to step 5:
20 can be fit into 80 4 times, resulting in a remainder of 0.
Write down 4 as next digit of the result. 
Result so far: 1894.0
If we subtract 80 from 80, we get 0.
Take the next digit (9) from the dividend and append it to 0, then repeat: 9 / 20

Advancing to step 6:
9 divided by 20 is 0 with a remainder of 9.
Write down 0 as next digit of the result. 
Result so far: 18940.0
The remainder is 9 after subtracting 0 from 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

On to step 7:
20 goes into 90 4 times with a remainder of 10.
Record the quotient 4 as the next digit in the result. 
Result so far: 18940.4
If we subtract 80 from 90, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

On to step 8:
20 can be fit into 100 5 times, resulting in a remainder of 0.
Write down 5 as next digit of the result. 
Result so far: 18940.45
Subtracting 100 from 100 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 9:
20 can be fit into 0 0 times, resulting in a remainder of 0.
The next digit of our result is 0. 
Result so far: 18940.45
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 10:
When dividing 0 by 20, we get 0 with a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 18940.45
Subtract 0 from 0 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

After the division, we end up with 18940.45 and a remainder of 0.0.