Let's divide 757641 by 21
The aim is to understand the frequency of 21 in 757641.

Step 1:
7 divided by 21 is 0 with a remainder of 7.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 7 leaves us with 7.
Grab the next digit (5) from the dividend, add it to 7, then carry on: 75 / 21

Let's proceed to step 2:
When dividing 75 by 21, we get 3 with a remainder of 12.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
If we take 63 away from 75, we end up with 12.
Take the next digit (7) from the dividend and append it to 12, then repeat: 127 / 21

Step 3:
21 goes into 127 6 times with a remainder of 1.
Put 6 as the next digit of the answer. 
Result so far: 36.0
If we subtract 126 from 127, we get 1.
Fetch the next digit (6) from the dividend, attach it to 1 and continue: 16 / 21

Going ahead to step 4:
16 divided by 21 is 0 with a remainder of 16.
Use 0 as the next digit of our solution. 
Result so far: 360.0
The remainder is 16 after subtracting 0 from 16.
Append the next digit (4) from the dividend to 16 and continue with: 164 / 21

Step 5:
164 divided by 21 is 7 with a remainder of 17.
Put 7 as the next digit of the answer. 
Result so far: 3607.0
The remainder is 17 after subtracting 147 from 164.
Bring next digit (1) of the dividend behind the 17 and repeat the process: 171 / 21

Step 6:
When dividing 171 by 21, we get 8 with a remainder of 3.
The next digit of our result is 8. 
Result so far: 36078.0
If we take 168 away from 171, we end up 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.

Step 7:
If we divide 30 by 21, we get 1 and a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 36078.1
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.

Advancing to step 8:
The number 21 fits into 90 4 times, leaving a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 36078.14
Deduct 84 from 90 and we're left 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.

Step 9:
21 can be fit into 60 2 times, resulting in a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 36078.142
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.

Going ahead to step 10:
When dividing 180 by 21, we get 8 with a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 36078.1428
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 11:
21 can be fit into 120 5 times, resulting in a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 36078.14285
Subtract 105 from 120 to 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.

Let's proceed to step 12:
If we divide 150 by 21, we get 7 and a remainder of 3.
Write down 7 as next digit of the result. 
Result so far: 36078.142857
Subtracting 147 from 150 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.

On to step 13:
21 goes into 30 1 times with a remainder of 9.
The next digit of our result is 1. 
Result so far: 36078.1428571
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 14:
The number 21 fits into 90 4 times, leaving a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 36078.14285714
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.

Our division results in 36078.14285714 with a remaining 6e-09.