634778 divided by 21 
The aim is to understand the frequency of 21 in 634778.

Moving on to step 1:
6 divided by 21 is 0 with a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Grab the next digit (3) from the dividend, add it to 6, then carry on: 63 / 21

Let's proceed to step 2:
21 goes into 63 3 times with a remainder of 0.
Write down 3 as next digit of the result. 
Result so far: 3.0
If we subtract 63 from 63, we get 0.
Grab the next digit (4) from the dividend, add it to 0, then carry on: 4 / 21

Going ahead to step 3:
If we divide 4 by 21, we get 0 and a remainder of 4.
Use 0 as the next digit of our solution. 
Result so far: 30.0
Deduct 0 from 4 and we're left with 4.
Append the next digit (7) from the dividend to 4 and continue with: 47 / 21

Moving on to step 4:
If we divide 47 by 21, we get 2 and a remainder of 5.
Put 2 as the next digit of the answer. 
Result so far: 302.0
Subtract 42 from 47 to get 5.
Take the next digit (7) from the dividend and append it to 5, then repeat: 57 / 21

Going ahead to step 5:
21 can be fit into 57 2 times, resulting in a remainder of 15.
Write down 2 as next digit of the result. 
Result so far: 3022.0
Deduct 42 from 57 and we're left with 15.
Include the next digit (8) from the dividend after 15, then repeat: 158 / 21

Advancing to step 6:
21 can be fit into 158 7 times, resulting in a remainder of 11.
Write down 7 as next digit of the result. 
Result so far: 30227.0
Subtracting 147 from 158 leaves us 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 7:
If we divide 110 by 21, we get 5 and a remainder of 5.
The number 5 becomes the next digit in our result. 
Result so far: 30227.5
The remainder is 5 after subtracting 105 from 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Going ahead to step 8:
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: 30227.52
If we take 42 away from 50, we end up 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.

Step 9:
21 can be fit into 80 3 times, resulting in a remainder of 17.
Write down 3 as next digit of the result. 
Result so far: 30227.523
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.

Advancing to step 10:
If we divide 170 by 21, we get 8 and a remainder of 2.
Put 8 as the next digit of the answer. 
Result so far: 30227.5238
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.

Step 11:
21 goes into 20 0 times with a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 30227.5238
Subtracting 0 from 20 leaves us with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Moving on to step 12:
The number 21 fits into 200 9 times, leaving a remainder of 11.
Write down 9 as next digit of the result. 
Result so far: 30227.523809
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.

Let's proceed to step 13:
21 goes into 110 5 times with a remainder of 5.
Put 5 as the next digit of the answer. 
Result so far: 30227.5238095
Subtract 105 from 110 to 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.

On to step 14:
21 goes into 50 2 times with a remainder of 8.
The number 2 becomes the next digit in our result. 
Result so far: 30227.52380952
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.

The final outcome is 30227.52380952, with a leftover of 8e-09.