the original number could have been anything from 45 to 54
351.2
1.041
3142.8
45,46,47,48,49,50,51,52,53,54
5.4
It is 42, exactly as in the question.
16.9 is a rational number. 13.9 may or may not be rounded to the nearest hundredth percent. It depends on what the original number was.
The critical bit of information: the number after "nearest" is missing from the question.
5 dollars, if the original figure was the number of cents.
The answer will depend on the degree to which the number is rounded. Without any indication of that, it is not possible to answer the question sensibly.
100
I am realising that the question can be asking two things. Q1) what is 720 rounded to the nearest 10? A1) 720, as 720 is divisible by 10 Q2) A number has been rounded to the nearest 10, and the answer is 720, but what was the original number? A2) the number could have been any number between 715 and 724.99999.... hope it helps