77375826 divided by 21 
The aim is to understand the frequency of 21 in 77375826.

Step 1:
21 goes into 7 0 times with a remainder of 7.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 7 to get 7.
Take the next digit (7) from the dividend and append it to 7, then repeat: 77 / 21

On to step 2:
When dividing 77 by 21, we get 3 with a remainder of 14.
The next digit of our result is 3. 
Result so far: 3.0
Deduct 63 from 77 and we're left with 14.
Grab the next digit (3) from the dividend, add it to 14, then carry on: 143 / 21

Step 3:
143 divided by 21 is 6 with a remainder of 17.
The number 6 becomes the next digit in our result. 
Result so far: 36.0
Subtract 126 from 143 to get 17.
Include the next digit (7) from the dividend after 17, then repeat: 177 / 21

Advancing to step 4:
When dividing 177 by 21, we get 8 with a remainder of 9.
Record the quotient 8 as the next digit in the result. 
Result so far: 368.0
Deduct 168 from 177 and we're left with 9.
Append the next digit (5) from the dividend to 9 and continue with: 95 / 21

Let's proceed to step 5:
95 divided by 21 is 4 with a remainder of 11.
Write down 4 as next digit of the result. 
Result so far: 3684.0
Subtracting 84 from 95 leaves us with 11.
Bring next digit (8) of the dividend behind the 11 and repeat the process: 118 / 21

Step 6:
21 can be fit into 118 5 times, resulting in a remainder of 13.
Record the quotient 5 as the next digit in the result. 
Result so far: 36845.0
Subtracting 105 from 118 leaves us with 13.
Include the next digit (2) from the dividend after 13, then repeat: 132 / 21

On to step 7:
When dividing 132 by 21, we get 6 with a remainder of 6.
The number 6 becomes the next digit in our result. 
Result so far: 368456.0
Subtracting 126 from 132 leaves us with 6.
Fetch the next digit (6) from the dividend, attach it to 6 and continue: 66 / 21

On to step 8:
If we divide 66 by 21, we get 3 and a remainder of 3.
Record the quotient 3 as the next digit in the result. 
Result so far: 3684563.0
Subtracting 63 from 66 leaves us with 3.
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 9:
The number 21 fits into 30 1 times, leaving a remainder of 9.
Use 1 as the next digit of our solution. 
Result so far: 3684563.1
If we take 21 away from 30, we end up with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Going ahead to step 10:
When dividing 90 by 21, we get 4 with a remainder of 6.
The next digit of our result is 4. 
Result so far: 3684563.14
The remainder is 6 after subtracting 84 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 11:
When dividing 60 by 21, we get 2 with a remainder of 18.
The next digit of our result is 2. 
Result so far: 3684563.142
The remainder is 18 after subtracting 42 from 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Moving on to step 12:
180 divided by 21 is 8 with a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 3684563.1428
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.

Step 13:
When dividing 120 by 21, we get 5 with a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 3684563.14285
If we subtract 105 from 120, we get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Advancing to step 14:
When dividing 150 by 21, we get 7 with a remainder of 3.
Put 7 as the next digit of the answer. 
Result so far: 3684563.142857
If we subtract 147 from 150, we 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.

Going ahead to step 15:
If we divide 30 by 21, we get 1 and a remainder of 9.
The number 1 becomes the next digit in our result. 
Result so far: 3684563.1428571
Subtracting 21 from 30 leaves us with 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 16:
When dividing 90 by 21, we get 4 with a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 3684563.14285714
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.

The final outcome is 3684563.14285714, with a leftover of 6e-09.