We divide 639061 by 21
The aim is to understand the frequency of 21 in 639061.

Going ahead to step 1:
6 divided by 21 is 0 with a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 6 and we're left with 6.
Fetch the next digit (3) from the dividend, attach it to 6 and continue: 63 / 21

Going ahead to step 2:
63 divided by 21 is 3 with a remainder of 0.
Put 3 as the next digit of the answer. 
Result so far: 3.0
The remainder is 0 after subtracting 63 from 63.
Bring next digit (9) of the dividend behind the 0 and repeat the process: 9 / 21

On to step 3:
9 divided by 21 is 0 with a remainder of 9.
The next digit of our result is 0. 
Result so far: 30.0
Deduct 0 from 9 and we're left with 9.
Append the next digit (0) from the dividend to 9 and continue with: 90 / 21

Advancing to step 4:
The number 21 fits into 90 4 times, leaving a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 304.0
Subtract 84 from 90 to get 6.
Bring next digit (6) of the dividend behind the 6 and repeat the process: 66 / 21

On to step 5:
21 can be fit into 66 3 times, resulting in a remainder of 3.
The number 3 becomes the next digit in our result. 
Result so far: 3043.0
If we take 63 away from 66, we end up with 3.
Fetch the next digit (1) from the dividend, attach it to 3 and continue: 31 / 21

Going ahead to step 6:
When dividing 31 by 21, we get 1 with a remainder of 10.
Write down 1 as next digit of the result. 
Result so far: 30431.0
If we subtract 21 from 31, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Moving on to step 7:
When dividing 100 by 21, we get 4 with a remainder of 16.
The next digit of our result is 4. 
Result so far: 30431.4
Subtract 84 from 100 to get 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Going ahead to step 8:
The number 21 fits into 160 7 times, leaving a remainder of 13.
Write down 7 as next digit of the result. 
Result so far: 30431.47
If we subtract 147 from 160, we get 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Going ahead to step 9:
21 can be fit into 130 6 times, resulting in a remainder of 4.
Use 6 as the next digit of our solution. 
Result so far: 30431.476
Subtracting 126 from 130 leaves us with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Let's proceed to step 10:
21 can be fit into 40 1 times, resulting in a remainder of 19.
Record the quotient 1 as the next digit in the result. 
Result so far: 30431.4761
If we subtract 21 from 40, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

On to step 11:
190 divided by 21 is 9 with a remainder of 1.
Record the quotient 9 as the next digit in the result. 
Result so far: 30431.47619
If we take 189 away from 190, we end up with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Advancing to step 12:
When dividing 10 by 21, we get 0 with a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 30431.47619
The remainder is 10 after subtracting 0 from 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Going ahead to step 13:
21 goes into 100 4 times with a remainder of 16.
The next digit of our result is 4. 
Result so far: 30431.4761904
Subtracting 84 from 100 leaves us with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

On to step 14:
21 goes into 160 7 times with a remainder of 13.
The next digit of our result is 7. 
Result so far: 30431.47619047
If we take 147 away from 160, we end up with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

In conclusion, the division gives 30431.47619047 with a balance of 1.3e-08.