234220 divided by 21 
The aim is to understand the frequency of 21 in 234220.

On to step 1:
If we divide 2 by 21, we get 0 and a remainder of 2.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 2 leaves us with 2.
Bring next digit (3) of the dividend behind the 2 and repeat the process: 23 / 21

Advancing to step 2:
21 can be fit into 23 1 times, resulting in a remainder of 2.
Write down 1 as next digit of the result. 
Result so far: 1.0
Deduct 21 from 23 and we're left with 2.
Bring next digit (4) of the dividend behind the 2 and repeat the process: 24 / 21

Step 3:
If we divide 24 by 21, we get 1 and a remainder of 3.
Write down 1 as next digit of the result. 
Result so far: 11.0
Deduct 21 from 24 and we're left with 3.
Bring next digit (2) of the dividend behind the 3 and repeat the process: 32 / 21

On to step 4:
The number 21 fits into 32 1 times, leaving a remainder of 11.
Record the quotient 1 as the next digit in the result. 
Result so far: 111.0
Subtract 21 from 32 to get 11.
Grab the next digit (2) from the dividend, add it to 11, then carry on: 112 / 21

Going ahead to step 5:
112 divided by 21 is 5 with a remainder of 7.
The next digit of our result is 5. 
Result so far: 1115.0
The remainder is 7 after subtracting 105 from 112.
Include the next digit (0) from the dividend after 7, then repeat: 70 / 21

Moving on to step 6:
If we divide 70 by 21, we get 3 and a remainder of 7.
Write down 3 as next digit of the result. 
Result so far: 11153.0
If we subtract 63 from 70, we get 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Going ahead to step 7:
21 can be fit into 70 3 times, resulting in a remainder of 7.
The number 3 becomes the next digit in our result. 
Result so far: 11153.3
Deduct 63 from 70 and we're left with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Moving on to step 8:
21 can be fit into 70 3 times, resulting in a remainder of 7.
Put 3 as the next digit of the answer. 
Result so far: 11153.33
Deduct 63 from 70 and we're left with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

The quotient of the division is 11153.33, and the remainder is 0.007.