21530303 ÷ 256 
We want to figure out the number of times 21530303 can be divided by 256.

Step 1:
If we divide 2 by 256, we get 0 and a remainder of 2.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 2, we get 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 256

Going ahead to step 2:
The number 256 fits into 21 0 times, leaving a remainder of 21.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 21 and we're left with 21.
Grab the next digit (5) from the dividend, add it to 21, then carry on: 215 / 256

Going ahead to step 3:
256 goes into 215 0 times with a remainder of 215.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 215 to get 215.
Append the next digit (3) from the dividend to 215 and continue with: 2153 / 256

On to step 4:
256 goes into 2153 8 times with a remainder of 105.
Record the quotient 8 as the next digit in the result. 
Result so far: 8.0
If we subtract 2048 from 2153, we get 105.
Bring next digit (0) of the dividend behind the 105 and repeat the process: 1050 / 256

Advancing to step 5:
1050 divided by 256 is 4 with a remainder of 26.
Write down 4 as next digit of the result. 
Result so far: 84.0
Subtracting 1024 from 1050 leaves us with 26.
Append the next digit (3) from the dividend to 26 and continue with: 263 / 256

Let's proceed to step 6:
The number 256 fits into 263 1 times, leaving a remainder of 7.
The number 1 becomes the next digit in our result. 
Result so far: 841.0
The remainder is 7 after subtracting 256 from 263.
Append the next digit (0) from the dividend to 7 and continue with: 70 / 256

Let's proceed to step 7:
The number 256 fits into 70 0 times, leaving a remainder of 70.
Write down 0 as next digit of the result. 
Result so far: 8410.0
Subtracting 0 from 70 leaves us with 70.
Bring next digit (3) of the dividend behind the 70 and repeat the process: 703 / 256

Step 8:
If we divide 703 by 256, we get 2 and a remainder of 191.
The next digit of our result is 2. 
Result so far: 84102.0
Subtract 512 from 703 to get 191.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1910, and continue the process.

Going ahead to step 9:
The number 256 fits into 1910 7 times, leaving a remainder of 118.
Write down 7 as next digit of the result. 
Result so far: 84102.7
Subtract 1792 from 1910 to get 118.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1180, and continue the process.

Moving on to step 10:
When dividing 1180 by 256, we get 4 with a remainder of 156.
The number 4 becomes the next digit in our result. 
Result so far: 84102.74
If we subtract 1024 from 1180, we get 156.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1560, and continue the process.

Moving on to step 11:
When dividing 1560 by 256, we get 6 with a remainder of 24.
Use 6 as the next digit of our solution. 
Result so far: 84102.746
Deduct 1536 from 1560 and we're left with 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Step 12:
240 divided by 256 is 0 with a remainder of 240.
Put 0 as the next digit of the answer. 
Result so far: 84102.746
Deduct 0 from 240 and we're left with 240.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2400, and continue the process.

Moving on to step 13:
256 goes into 2400 9 times with a remainder of 96.
Put 9 as the next digit of the answer. 
Result so far: 84102.74609
Deduct 2304 from 2400 and we're left with 96.
Since there are no more digits in the dividend, we add a zero to the remainder making it 960, and continue the process.

On to step 14:
If we divide 960 by 256, we get 3 and a remainder of 192.
Write down 3 as next digit of the result. 
Result so far: 84102.746093
If we take 768 away from 960, we end up 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.

Going ahead to step 15:
256 can be fit into 1920 7 times, resulting in a remainder of 128.
Record the quotient 7 as the next digit in the result. 
Result so far: 84102.7460937
Subtract 1792 from 1920 to get 128.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1280, and continue the process.

Moving on to step 16:
256 can be fit into 1280 5 times, resulting in a remainder of 0.
The next digit of our result is 5. 
Result so far: 84102.74609375
Subtracting 1280 from 1280 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

After the division, we end up with 84102.74609375 and a remainder of 0.0.