521515 ÷ 30 
We're looking to find how many times 30 goes into 521515.

Let's proceed to step 1:
5 divided by 30 is 0 with a remainder of 5.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 5 to get 5.
Append the next digit (2) from the dividend to 5 and continue with: 52 / 30

Step 2:
If we divide 52 by 30, we get 1 and a remainder of 22.
Use 1 as the next digit of our solution. 
Result so far: 1.0
If we take 30 away from 52, we end up with 22.
Bring next digit (1) of the dividend behind the 22 and repeat the process: 221 / 30

Advancing to step 3:
30 can be fit into 221 7 times, resulting in a remainder of 11.
The number 7 becomes the next digit in our result. 
Result so far: 17.0
Subtract 210 from 221 to get 11.
Grab the next digit (5) from the dividend, add it to 11, then carry on: 115 / 30

Advancing to step 4:
115 divided by 30 is 3 with a remainder of 25.
The number 3 becomes the next digit in our result. 
Result so far: 173.0
Subtracting 90 from 115 leaves us with 25.
Include the next digit (1) from the dividend after 25, then repeat: 251 / 30

Moving on to step 5:
30 can be fit into 251 8 times, resulting in a remainder of 11.
Record the quotient 8 as the next digit in the result. 
Result so far: 1738.0
Subtract 240 from 251 to get 11.
Grab the next digit (5) from the dividend, add it to 11, then carry on: 115 / 30

Advancing to step 6:
If we divide 115 by 30, we get 3 and a remainder of 25.
The number 3 becomes the next digit in our result. 
Result so far: 17383.0
Subtract 90 from 115 to get 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Let's proceed to step 7:
250 divided by 30 is 8 with a remainder of 10.
Put 8 as the next digit of the answer. 
Result so far: 17383.8
Subtract 240 from 250 to get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

On to step 8:
When dividing 100 by 30, we get 3 with a remainder of 10.
Put 3 as the next digit of the answer. 
Result so far: 17383.83
Deduct 90 from 100 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 9:
If we divide 100 by 30, we get 3 and a remainder of 10.
Put 3 as the next digit of the answer. 
Result so far: 17383.833
Subtract 90 from 100 to get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

The final result is 17383.833 with a remainder of 0.001.