The second place to the right after the decimal is the hundredth, so basically, to round, you cut off the rest of the decimal places afterwards. If the number after the hundredth is at or above 5, you should make the hundredth 1 higher, but if it is 4 or below, you will just leave it as is. In this case, 3.047 rounds to 3.05. There really is not any math work to show, but just the explanation.<span />
Make 15 into an improper fraction (every number is a fraction over 1) so multiply the numerator(15) and the denominator(1) by 10 to get 150/10 then add 150/10 to 7/10 to get 157/10