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So this interpretation does work, but isn't really necessary. The point is that 5 1000^{th}'s = ½ 100^{th}. So if you write it with the fraction, it is the 100^{th} place that holds the ½, not the 1000^{th} place, otherwise you have changed it from 0.245 to 0.2405. Thus in 0.24 ½, you have a 0 in the one's place, 2 in the tenths place, and 4½ in the hundredths place. This is equivalent to 0 in the ones, 2 in the tenths, 4 in the hundredths and 5 in the thousandths, but not equivalent to 0 in the ones, 2 in the tenths, 4 in the hundredths and ½ in the thousandths. Remember that when writing numbers, the goal is to communicate effectively and unambiguously. If a student gave me an answer on a test and wrote 0.24 ½ instead of 0.245, I would probably take off half a mark for the lack of clarity. Hope this helps,  


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