52188 ÷ 21 
The aim is to understand the frequency of 21 in 52188.

Let's proceed to step 1:
When dividing 5 by 21, we get 0 with a remainder of 5.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Append the next digit (2) from the dividend to 5 and continue with: 52 / 21

Advancing to step 2:
21 goes into 52 2 times with a remainder of 10.
Record the quotient 2 as the next digit in the result. 
Result so far: 2.0
If we subtract 42 from 52, we get 10.
Append the next digit (1) from the dividend to 10 and continue with: 101 / 21

Advancing to step 3:
If we divide 101 by 21, we get 4 and a remainder of 17.
Write down 4 as next digit of the result. 
Result so far: 24.0
Subtracting 84 from 101 leaves us with 17.
Append the next digit (8) from the dividend to 17 and continue with: 178 / 21

Advancing to step 4:
21 goes into 178 8 times with a remainder of 10.
Write down 8 as next digit of the result. 
Result so far: 248.0
The remainder is 10 after subtracting 168 from 178.
Include the next digit (8) from the dividend after 10, then repeat: 108 / 21

Moving on to step 5:
If we divide 108 by 21, we get 5 and a remainder of 3.
Put 5 as the next digit of the answer. 
Result so far: 2485.0
If we subtract 105 from 108, we get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Moving on to step 6:
When dividing 30 by 21, we get 1 with a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 2485.1
Subtract 21 from 30 to 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.

Let's proceed to step 7:
90 divided by 21 is 4 with a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 2485.14
If we take 84 away from 90, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Step 8:
When dividing 60 by 21, we get 2 with a remainder of 18.
The number 2 becomes the next digit in our result. 
Result so far: 2485.142
Subtract 42 from 60 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.

Going ahead to step 9:
The number 21 fits into 180 8 times, leaving a remainder of 12.
Record the quotient 8 as the next digit in the result. 
Result so far: 2485.1428
If we subtract 168 from 180, we get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Let's proceed to step 10:
If we divide 120 by 21, we get 5 and a remainder of 15.
Use 5 as the next digit of our solution. 
Result so far: 2485.14285
If we subtract 105 from 120, 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.

Advancing to step 11:
The number 21 fits into 150 7 times, leaving a remainder of 3.
Write down 7 as next digit of the result. 
Result so far: 2485.142857
If we take 147 away from 150, we end up 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.

Step 12:
30 divided by 21 is 1 with a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 2485.1428571
Subtracting 21 from 30 leaves us with 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 13:
If we divide 90 by 21, we get 4 and a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 2485.14285714
The remainder is 6 after subtracting 84 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

The quotient of the division is 2485.14285714, and the remainder is 6e-09.