Which set of numbers best describes the displayed weights on a digital scale that shows each weight to the nearest half pound?

The answer is Real Numbers.   The Real Number best describes the displayed weights on a digital scale that shows each weight to the nearest half pound.  Although Rational  numbers can be written as a decimal or fraction, it is actually a set of Real Numbers.  The displayed weights that shows each weight to the nearest half pound gives a terminating decimal number, thus it is best described by Real Numbers.