We're dividing 580879 by 21 
The aim is to understand the frequency of 21 in 580879.

Advancing to step 1:
21 goes into 5 0 times with a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 5 and we're left with 5.
Fetch the next digit (8) from the dividend, attach it to 5 and continue: 58 / 21

Advancing to step 2:
21 goes into 58 2 times with a remainder of 16.
Use 2 as the next digit of our solution. 
Result so far: 2.0
Subtract 42 from 58 to get 16.
Grab the next digit (0) from the dividend, add it to 16, then carry on: 160 / 21

On to step 3:
If we divide 160 by 21, we get 7 and a remainder of 13.
Put 7 as the next digit of the answer. 
Result so far: 27.0
Deduct 147 from 160 and we're left with 13.
Append the next digit (8) from the dividend to 13 and continue with: 138 / 21

Let's proceed to step 4:
138 divided by 21 is 6 with a remainder of 12.
Use 6 as the next digit of our solution. 
Result so far: 276.0
Subtract 126 from 138 to get 12.
Bring next digit (7) of the dividend behind the 12 and repeat the process: 127 / 21

Let's proceed to step 5:
21 goes into 127 6 times with a remainder of 1.
Record the quotient 6 as the next digit in the result. 
Result so far: 2766.0
Deduct 126 from 127 and we're left with 1.
Grab the next digit (9) from the dividend, add it to 1, then carry on: 19 / 21

Going ahead to step 6:
21 can be fit into 19 0 times, resulting in a remainder of 19.
Put 0 as the next digit of the answer. 
Result so far: 27660.0
Deduct 0 from 19 and we're left with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Moving on to step 7:
21 can be fit into 190 9 times, resulting in a remainder of 1.
Put 9 as the next digit of the answer. 
Result so far: 27660.9
The remainder is 1 after subtracting 189 from 190.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 8:
21 goes into 10 0 times with a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 27660.9
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.

On to step 9:
The number 21 fits into 100 4 times, leaving a remainder of 16.
The number 4 becomes the next digit in our result. 
Result so far: 27660.904
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.

Moving on to step 10:
When dividing 160 by 21, we get 7 with a remainder of 13.
Write down 7 as next digit of the result. 
Result so far: 27660.9047
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.

Let's proceed to step 11:
If we divide 130 by 21, we get 6 and a remainder of 4.
Write down 6 as next digit of the result. 
Result so far: 27660.90476
If we take 126 away from 130, we end up 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.

Going ahead to step 12:
If we divide 40 by 21, we get 1 and a remainder of 19.
Put 1 as the next digit of the answer. 
Result so far: 27660.904761
Deduct 21 from 40 and we're left with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Step 13:
21 goes into 190 9 times with a remainder of 1.
The number 9 becomes the next digit in our result. 
Result so far: 27660.9047619
Deduct 189 from 190 and we're left 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.

Going ahead to step 14:
21 can be fit into 10 0 times, resulting in a remainder of 10.
The next digit of our result is 0. 
Result so far: 27660.9047619
Subtracting 0 from 10 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Our division results in 27660.9047619 with a remaining 1e-08.