You originally said "my question isn't about rounding"......so, I assumed you KNEW how to round a number, but had a question about what "15 with a line on top" meant.
36.0151515151515151515......
You are to round to 6 decimal places. Find the number in the 6th decimal place:
36.015151515151515......
Now, look at the digit in the place immediately to the right of that 6th place. If what is there is less than 5, drop all of the digits after the 6th one. If what is there is 5 or more, INCREASE the digit in the 6th place by 1, and drop all the remaining digits after the 6th one.
You've got a 1 in the 6th place. Immediately to the right of that is a 5. So, increase that 1 by 1, to get 2, and drop all of the digits after that:
36.015152
Apparently your question WAS about rounding after all.