We look at the division of 21291636 by 672 
The aim is to understand the frequency of 672 in 21291636.

Moving on to step 1:
When dividing 2 by 672, we get 0 with a remainder of 2.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we subtract 0 from 2, we get 2.
Grab the next digit (1) from the dividend, add it to 2, then carry on: 21 / 672

Moving on to step 2:
If we divide 21 by 672, we get 0 and a remainder of 21.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 21, we end up with 21.
Fetch the next digit (2) from the dividend, attach it to 21 and continue: 212 / 672

Advancing to step 3:
When dividing 212 by 672, we get 0 with a remainder of 212.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 212 leaves us with 212.
Append the next digit (9) from the dividend to 212 and continue with: 2129 / 672

Let's proceed to step 4:
672 goes into 2129 3 times with a remainder of 113.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
Subtract 2016 from 2129 to get 113.
Grab the next digit (1) from the dividend, add it to 113, then carry on: 1131 / 672

Step 5:
When dividing 1131 by 672, we get 1 with a remainder of 459.
Write down 1 as next digit of the result. 
Result so far: 31.0
Subtracting 672 from 1131 leaves us with 459.
Include the next digit (6) from the dividend after 459, then repeat: 4596 / 672

Advancing to step 6:
4596 divided by 672 is 6 with a remainder of 564.
The number 6 becomes the next digit in our result. 
Result so far: 316.0
If we take 4032 away from 4596, we end up with 564.
Append the next digit (3) from the dividend to 564 and continue with: 5643 / 672

On to step 7:
If we divide 5643 by 672, we get 8 and a remainder of 267.
The next digit of our result is 8. 
Result so far: 3168.0
Subtract 5376 from 5643 to get 267.
Take the next digit (6) from the dividend and append it to 267, then repeat: 2676 / 672

Going ahead to step 8:
672 goes into 2676 3 times with a remainder of 660.
Use 3 as the next digit of our solution. 
Result so far: 31683.0
The remainder is 660 after subtracting 2016 from 2676.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6600, and continue the process.

Going ahead to step 9:
672 goes into 6600 9 times with a remainder of 552.
Put 9 as the next digit of the answer. 
Result so far: 31683.9
The remainder is 552 after subtracting 6048 from 6600.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5520, and continue the process.

On to step 10:
672 goes into 5520 8 times with a remainder of 144.
The next digit of our result is 8. 
Result so far: 31683.98
Subtract 5376 from 5520 to get 144.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1440, and continue the process.

Step 11:
672 goes into 1440 2 times with a remainder of 96.
The number 2 becomes the next digit in our result. 
Result so far: 31683.982
If we subtract 1344 from 1440, we get 96.
Since there are no more digits in the dividend, we add a zero to the remainder making it 960, and continue the process.

Advancing to step 12:
672 goes into 960 1 times with a remainder of 288.
The number 1 becomes the next digit in our result. 
Result so far: 31683.9821
Deduct 672 from 960 and we're left with 288.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2880, and continue the process.

Let's proceed to step 13:
2880 divided by 672 is 4 with a remainder of 192.
Use 4 as the next digit of our solution. 
Result so far: 31683.98214
Deduct 2688 from 2880 and we're left with 192.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1920, and continue the process.

Let's proceed to step 14:
1920 divided by 672 is 2 with a remainder of 576.
The next digit of our result is 2. 
Result so far: 31683.982142
Deduct 1344 from 1920 and we're left with 576.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5760, and continue the process.

Moving on to step 15:
5760 divided by 672 is 8 with a remainder of 384.
The number 8 becomes the next digit in our result. 
Result so far: 31683.9821428
If we subtract 5376 from 5760, we get 384.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3840, and continue the process.

Advancing to step 16:
3840 divided by 672 is 5 with a remainder of 480.
Put 5 as the next digit of the answer. 
Result so far: 31683.98214285
Deduct 3360 from 3840 and we're left with 480.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4800, and continue the process.

The final result is 31683.98214285 with a remainder of 4.8e-07.