21505617 ÷ 587 
The aim is to understand the frequency of 587 in 21505617.

Step 1:
If we divide 2 by 587, we get 0 and a remainder of 2.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 2 after subtracting 0 from 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 587

On to step 2:
The number 587 fits into 21 0 times, leaving a remainder of 21.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 21 after subtracting 0 from 21.
Include the next digit (5) from the dividend after 21, then repeat: 215 / 587

Moving on to step 3:
587 goes into 215 0 times with a remainder of 215.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 215, we end up with 215.
Include the next digit (0) from the dividend after 215, then repeat: 2150 / 587

Step 4:
587 goes into 2150 3 times with a remainder of 389.
Write down 3 as next digit of the result. 
Result so far: 3.0
Subtracting 1761 from 2150 leaves us with 389.
Bring next digit (5) of the dividend behind the 389 and repeat the process: 3895 / 587

Advancing to step 5:
587 can be fit into 3895 6 times, resulting in a remainder of 373.
Put 6 as the next digit of the answer. 
Result so far: 36.0
If we take 3522 away from 3895, we end up with 373.
Fetch the next digit (6) from the dividend, attach it to 373 and continue: 3736 / 587

On to step 6:
587 goes into 3736 6 times with a remainder of 214.
The number 6 becomes the next digit in our result. 
Result so far: 366.0
Subtract 3522 from 3736 to get 214.
Bring next digit (1) of the dividend behind the 214 and repeat the process: 2141 / 587

On to step 7:
When dividing 2141 by 587, we get 3 with a remainder of 380.
Write down 3 as next digit of the result. 
Result so far: 3663.0
The remainder is 380 after subtracting 1761 from 2141.
Bring next digit (7) of the dividend behind the 380 and repeat the process: 3807 / 587

Going ahead to step 8:
587 can be fit into 3807 6 times, resulting in a remainder of 285.
Use 6 as the next digit of our solution. 
Result so far: 36636.0
The remainder is 285 after subtracting 3522 from 3807.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2850, and continue the process.

Step 9:
The number 587 fits into 2850 4 times, leaving a remainder of 502.
The next digit of our result is 4. 
Result so far: 36636.4
The remainder is 502 after subtracting 2348 from 2850.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5020, and continue the process.

Let's proceed to step 10:
When dividing 5020 by 587, we get 8 with a remainder of 324.
The number 8 becomes the next digit in our result. 
Result so far: 36636.48
Deduct 4696 from 5020 and we're left with 324.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3240, and continue the process.

Step 11:
If we divide 3240 by 587, we get 5 and a remainder of 305.
Put 5 as the next digit of the answer. 
Result so far: 36636.485
Deduct 2935 from 3240 and we're left with 305.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3050, and continue the process.

Going ahead to step 12:
If we divide 3050 by 587, we get 5 and a remainder of 115.
The number 5 becomes the next digit in our result. 
Result so far: 36636.4855
Subtract 2935 from 3050 to get 115.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1150, and continue the process.

After the division, we end up with 36636.4855 and a remainder of 0.00115.