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  1. #1
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    Homework Help

    My daughter has two questions on her homework that we can't figure out. Hopefully someone can help us.

    (1)Explain what happens when you round 9,999.999 to any place.

    (2)Describe two real-world situations in which it makes sense to round numbers.
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  2. #2
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by edenhpu94 View Post
    My daughter has two questions on her homework that we can't figure out. Hopefully someone can help us.

    (1)Explain what happens when you round 9,999.999 to any place.
    What happens, is that 9 rounds up to 10, but if you did that in any position to the right of the first digit in the number this is what happens:

    Let's take your number 9,999.999:

    If we round the last digits up to the nearest one, we see that we have the following chain reaction:

    9,999.9(9+1)0\implies9,999.(9+1)00\implies9,99(9+1  ).000\implies9,9(9+1)0.000 \implies9,(9+1)00.000\implies (9+1),000.000\implies 10,000.000

    No matter where you start to round up, you will always end up with 10,000.000

    I hope this makes sense.

    (2)Describe two real-world situations in which it makes sense to round numbers.
    For example, if you measure someone's height. We usually say that someone is 6'1'', 5'7'', 5'10'', etc. Anything we measure is continuous; we can never give an exact value for it. There will always be rounding errors. Also, it wouldn't make sense to say that you're 5'11.1267844568395678923532479234...''

    Another example would be when dealing with money. The number representation of money never exceeds more than 2 decimal points to the right.

    For example, we may see that a bottle of soda may be \$1.25, but not \$1.25343

    Hopefully this makes sense!

    --Chris
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  3. #3
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    Rounding Off Decimals

    For a great animated/narrated explanation about rounding off decimals that is EASY to understand, check this:

    Mathematics.com.au - Rounding Off Decimals
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