We're dividing 8521 by 28 
We want to divide 8521 by 28.

Step 1:
The number 28 fits into 8 0 times, leaving a remainder of 8.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 8 after subtracting 0 from 8.
Bring next digit (5) of the dividend behind the 8 and repeat the process: 85 / 28

Step 2:
85 divided by 28 is 3 with a remainder of 1.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
If we take 84 away from 85, we end up with 1.
Append the next digit (2) from the dividend to 1 and continue with: 12 / 28

Let's proceed to step 3:
If we divide 12 by 28, we get 0 and a remainder of 12.
Write down 0 as next digit of the result. 
Result so far: 30.0
The remainder is 12 after subtracting 0 from 12.
Take the next digit (1) from the dividend and append it to 12, then repeat: 121 / 28

Step 4:
If we divide 121 by 28, we get 4 and a remainder of 9.
Record the quotient 4 as the next digit in the result. 
Result so far: 304.0
Subtracting 112 from 121 leaves us 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.

Advancing to step 5:
If we divide 90 by 28, we get 3 and a remainder of 6.
The next digit of our result is 3. 
Result so far: 304.3
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.

Moving on to step 6:
When dividing 60 by 28, we get 2 with a remainder of 4.
Record the quotient 2 as the next digit in the result. 
Result so far: 304.32
If we take 56 away from 60, we end up with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Moving on to step 7:
28 can be fit into 40 1 times, resulting in a remainder of 12.
Record the quotient 1 as the next digit in the result. 
Result so far: 304.321
If we take 28 away from 40, 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.

Advancing to step 8:
If we divide 120 by 28, we get 4 and a remainder of 8.
The next digit of our result is 4. 
Result so far: 304.3214
Subtracting 112 from 120 leaves us with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Advancing to step 9:
The number 28 fits into 80 2 times, leaving a remainder of 24.
Use 2 as the next digit of our solution. 
Result so far: 304.32142
Subtract 56 from 80 to get 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

On to step 10:
If we divide 240 by 28, we get 8 and a remainder of 16.
Put 8 as the next digit of the answer. 
Result so far: 304.321428
The remainder is 16 after subtracting 224 from 240.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Advancing to step 11:
28 can be fit into 160 5 times, resulting in a remainder of 20.
Put 5 as the next digit of the answer. 
Result so far: 304.3214285
Subtracting 140 from 160 leaves us with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Step 12:
200 divided by 28 is 7 with a remainder of 4.
The next digit of our result is 7. 
Result so far: 304.32142857
Subtracting 196 from 200 leaves us with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

The final outcome is 304.32142857, with a leftover of 4e-09.