We're dividing 50221436 by 21 
The aim is to understand the frequency of 21 in 50221436.

Going ahead to step 1:
When dividing 5 by 21, we get 0 with a remainder of 5.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 5, we end up with 5.
Fetch the next digit (0) from the dividend, attach it to 5 and continue: 50 / 21

Going ahead to step 2:
21 goes into 50 2 times with a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 2.0
The remainder is 8 after subtracting 42 from 50.
Bring next digit (2) of the dividend behind the 8 and repeat the process: 82 / 21

Going ahead to step 3:
21 can be fit into 82 3 times, resulting in a remainder of 19.
The number 3 becomes the next digit in our result. 
Result so far: 23.0
Subtracting 63 from 82 leaves us with 19.
Bring next digit (2) of the dividend behind the 19 and repeat the process: 192 / 21

Advancing to step 4:
The number 21 fits into 192 9 times, leaving a remainder of 3.
Write down 9 as next digit of the result. 
Result so far: 239.0
If we take 189 away from 192, we end up with 3.
Grab the next digit (1) from the dividend, add it to 3, then carry on: 31 / 21

Going ahead to step 5:
21 can be fit into 31 1 times, resulting in a remainder of 10.
Write down 1 as next digit of the result. 
Result so far: 2391.0
Deduct 21 from 31 and we're left with 10.
Grab the next digit (4) from the dividend, add it to 10, then carry on: 104 / 21

Advancing to step 6:
The number 21 fits into 104 4 times, leaving a remainder of 20.
The number 4 becomes the next digit in our result. 
Result so far: 23914.0
Deduct 84 from 104 and we're left with 20.
Bring next digit (3) of the dividend behind the 20 and repeat the process: 203 / 21

Let's proceed to step 7:
If we divide 203 by 21, we get 9 and a remainder of 14.
The number 9 becomes the next digit in our result. 
Result so far: 239149.0
Subtract 189 from 203 to get 14.
Bring next digit (6) of the dividend behind the 14 and repeat the process: 146 / 21

Step 8:
The number 21 fits into 146 6 times, leaving a remainder of 20.
Write down 6 as next digit of the result. 
Result so far: 2391496.0
The remainder is 20 after subtracting 126 from 146.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Going ahead to step 9:
21 goes into 200 9 times with a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 2391496.9
Deduct 189 from 200 and we're left with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Moving on to step 10:
21 can be fit into 110 5 times, resulting in a remainder of 5.
The next digit of our result is 5. 
Result so far: 2391496.95
If we take 105 away from 110, we end up with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Advancing to step 11:
When dividing 50 by 21, we get 2 with a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 2391496.952
Deduct 42 from 50 and we're left with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Going ahead to step 12:
If we divide 80 by 21, we get 3 and a remainder of 17.
Write down 3 as next digit of the result. 
Result so far: 2391496.9523
Deduct 63 from 80 and we're left 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 13:
21 goes into 170 8 times with a remainder of 2.
Use 8 as the next digit of our solution. 
Result so far: 2391496.95238
Deduct 168 from 170 and we're left with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Moving on to step 14:
If we divide 20 by 21, we get 0 and a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 2391496.95238
If we subtract 0 from 20, we get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Advancing to step 15:
21 can be fit into 200 9 times, resulting in a remainder of 11.
The next digit of our result is 9. 
Result so far: 2391496.9523809
If we take 189 away from 200, we end up with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

On to step 16:
21 goes into 110 5 times with a remainder of 5.
The next digit of our result is 5. 
Result so far: 2391496.95238095
If we subtract 105 from 110, we 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.

In conclusion, the division gives 2391496.95238095 with a balance of 5e-09.