We look at the division of 998214 by 21 
The aim is to understand the frequency of 21 in 998214.

On to step 1:
If we divide 9 by 21, we get 0 and a remainder of 9.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 9 after subtracting 0 from 9.
Fetch the next digit (9) from the dividend, attach it to 9 and continue: 99 / 21

Advancing to step 2:
21 goes into 99 4 times with a remainder of 15.
The number 4 becomes the next digit in our result. 
Result so far: 4.0
Deduct 84 from 99 and we're left with 15.
Fetch the next digit (8) from the dividend, attach it to 15 and continue: 158 / 21

Let's proceed to step 3:
When dividing 158 by 21, we get 7 with a remainder of 11.
Write down 7 as next digit of the result. 
Result so far: 47.0
The remainder is 11 after subtracting 147 from 158.
Bring next digit (2) of the dividend behind the 11 and repeat the process: 112 / 21

Advancing to step 4:
21 can be fit into 112 5 times, resulting in a remainder of 7.
Put 5 as the next digit of the answer. 
Result so far: 475.0
Subtracting 105 from 112 leaves us with 7.
Bring next digit (1) of the dividend behind the 7 and repeat the process: 71 / 21

Let's proceed to step 5:
The number 21 fits into 71 3 times, leaving a remainder of 8.
Put 3 as the next digit of the answer. 
Result so far: 4753.0
The remainder is 8 after subtracting 63 from 71.
Append the next digit (4) from the dividend to 8 and continue with: 84 / 21

On to step 6:
21 goes into 84 4 times with a remainder of 0.
Use 4 as the next digit of our solution. 
Result so far: 47534.0
If we subtract 84 from 84, we 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.

On to step 7:
When dividing 0 by 21, we get 0 with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 47534.0
If we subtract 0 from 0, we 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.

Going ahead to step 8:
21 goes into 0 0 times with a remainder of 0.
The next digit of our result is 0. 
Result so far: 47534.0
If we take 0 away from 0, we end up 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.

Our division results in 47534.0 with a remaining 0.0.