We divide 77976 by 21
The aim is to understand the frequency of 21 in 77976.

Advancing to step 1:
If we divide 7 by 21, we get 0 and a remainder of 7.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 7, we get 7.
Take the next digit (7) from the dividend and append it to 7, then repeat: 77 / 21

Moving on to step 2:
77 divided by 21 is 3 with a remainder of 14.
Write down 3 as next digit of the result. 
Result so far: 3.0
Subtract 63 from 77 to get 14.
Fetch the next digit (9) from the dividend, attach it to 14 and continue: 149 / 21

Let's proceed to step 3:
21 goes into 149 7 times with a remainder of 2.
Write down 7 as next digit of the result. 
Result so far: 37.0
If we subtract 147 from 149, we get 2.
Include the next digit (7) from the dividend after 2, then repeat: 27 / 21

On to step 4:
If we divide 27 by 21, we get 1 and a remainder of 6.
The number 1 becomes the next digit in our result. 
Result so far: 371.0
The remainder is 6 after subtracting 21 from 27.
Fetch the next digit (6) from the dividend, attach it to 6 and continue: 66 / 21

Let's proceed to step 5:
21 can be fit into 66 3 times, resulting in a remainder of 3.
The next digit of our result is 3. 
Result so far: 3713.0
Subtract 63 from 66 to get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

On to step 6:
The number 21 fits into 30 1 times, leaving a remainder of 9.
The next digit of our result is 1. 
Result so far: 3713.1
Subtract 21 from 30 to get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Advancing to step 7:
90 divided by 21 is 4 with a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 3713.14
If we take 84 away from 90, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Moving on to step 8:
21 goes into 60 2 times with a remainder of 18.
The next digit of our result is 2. 
Result so far: 3713.142
Deduct 42 from 60 and we're left with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Advancing to step 9:
The number 21 fits into 180 8 times, leaving a remainder of 12.
Write down 8 as next digit of the result. 
Result so far: 3713.1428
If we take 168 away from 180, we end up with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Moving on to step 10:
When dividing 120 by 21, we get 5 with a remainder of 15.
The next digit of our result is 5. 
Result so far: 3713.14285
Subtracting 105 from 120 leaves us with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Let's proceed to step 11:
21 can be fit into 150 7 times, resulting in a remainder of 3.
The next digit of our result is 7. 
Result so far: 3713.142857
The remainder is 3 after subtracting 147 from 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Moving on to step 12:
30 divided by 21 is 1 with a remainder of 9.
The next digit of our result is 1. 
Result so far: 3713.1428571
If we subtract 21 from 30, we get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Let's proceed to step 13:
21 goes into 90 4 times with a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 3713.14285714
If we subtract 84 from 90, we get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

The quotient of the division is 3713.14285714, and the remainder is 6e-09.