21268489 divided by 643 
The aim is to understand the frequency of 643 in 21268489.

Moving on to step 1:
If we divide 2 by 643, we get 0 and a remainder of 2.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 2 and we're left with 2.
Fetch the next digit (1) from the dividend, attach it to 2 and continue: 21 / 643

Step 2:
643 can be fit into 21 0 times, resulting in a remainder of 21.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 21 to get 21.
Append the next digit (2) from the dividend to 21 and continue with: 212 / 643

On to step 3:
The number 643 fits into 212 0 times, leaving a remainder of 212.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 212 and we're left with 212.
Fetch the next digit (6) from the dividend, attach it to 212 and continue: 2126 / 643

Moving on to step 4:
643 goes into 2126 3 times with a remainder of 197.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
If we take 1929 away from 2126, we end up with 197.
Fetch the next digit (8) from the dividend, attach it to 197 and continue: 1978 / 643

Advancing to step 5:
643 goes into 1978 3 times with a remainder of 49.
The number 3 becomes the next digit in our result. 
Result so far: 33.0
Subtract 1929 from 1978 to get 49.
Include the next digit (4) from the dividend after 49, then repeat: 494 / 643

Let's proceed to step 6:
643 goes into 494 0 times with a remainder of 494.
The next digit of our result is 0. 
Result so far: 330.0
Subtracting 0 from 494 leaves us with 494.
Fetch the next digit (8) from the dividend, attach it to 494 and continue: 4948 / 643

Step 7:
643 can be fit into 4948 7 times, resulting in a remainder of 447.
Use 7 as the next digit of our solution. 
Result so far: 3307.0
Deduct 4501 from 4948 and we're left with 447.
Append the next digit (9) from the dividend to 447 and continue with: 4479 / 643

Going ahead to step 8:
643 goes into 4479 6 times with a remainder of 621.
Put 6 as the next digit of the answer. 
Result so far: 33076.0
Deduct 3858 from 4479 and we're left with 621.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6210, and continue the process.

Going ahead to step 9:
6210 divided by 643 is 9 with a remainder of 423.
Put 9 as the next digit of the answer. 
Result so far: 33076.9
Subtracting 5787 from 6210 leaves us with 423.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4230, and continue the process.

On to step 10:
4230 divided by 643 is 6 with a remainder of 372.
The next digit of our result is 6. 
Result so far: 33076.96
If we subtract 3858 from 4230, we get 372.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3720, and continue the process.

Moving on to step 11:
The number 643 fits into 3720 5 times, leaving a remainder of 505.
Use 5 as the next digit of our solution. 
Result so far: 33076.965
If we subtract 3215 from 3720, we get 505.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5050, and continue the process.

Going ahead to step 12:
If we divide 5050 by 643, we get 7 and a remainder of 549.
Put 7 as the next digit of the answer. 
Result so far: 33076.9657
Subtract 4501 from 5050 to get 549.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5490, and continue the process.

Step 13:
When dividing 5490 by 643, we get 8 with a remainder of 346.
The next digit of our result is 8. 
Result so far: 33076.96578
Subtracting 5144 from 5490 leaves us with 346.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3460, and continue the process.

Let's proceed to step 14:
643 goes into 3460 5 times with a remainder of 245.
The next digit of our result is 5. 
Result so far: 33076.965785
Deduct 3215 from 3460 and we're left with 245.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2450, and continue the process.

Moving on to step 15:
If we divide 2450 by 643, we get 3 and a remainder of 521.
Put 3 as the next digit of the answer. 
Result so far: 33076.9657853
Subtract 1929 from 2450 to get 521.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5210, and continue the process.

Going ahead to step 16:
643 goes into 5210 8 times with a remainder of 66.
Write down 8 as next digit of the result. 
Result so far: 33076.96578538
If we subtract 5144 from 5210, we get 66.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

In conclusion, the division gives 33076.96578538 with a balance of 6.6e-08.