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Math Help - question i can't figure out

  1. #1
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    question i can't figure out

    " why do you think we round up when a 5 is the next digit to the right of the place in witch we are rounding ? "

    i'm guessing it has something to do with numbers starting out at zero ?
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  2. #2
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    0.5 is the same as one-half. If you are walking home from school and you are one-half of the distance to your home when it starts to rain, would you keep going home or turn around and head back to school?
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  3. #3
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    i still don't understand the reason for rounding up when its at 5, infact i don't understand the reasoning for rounding at all since if you didn't round you would have a more accurate number i would think...
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  4. #4
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    Do you think it would be reasonable to give everytime all the numbers in pi for example?

    One other thing... when you take a reading, you always take it to the nearest reading you can measure. If the exact length of something was 1.0652 cm, you will only be able to measure a length of 1 cm with a common ruler.

    Rounding off is a means to simplify numbers and remove unnecessary details. This eases work. Where some accuracy is required, then you don't round off.
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  5. #5
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    Quote Originally Posted by Unknown008 View Post
    Do you think it would be reasonable to give everytime all the numbers in pi for example?

    One other thing... when you take a reading, you always take it to the nearest reading you can measure. If the exact length of something was 1.0652 cm, you will only be able to measure a length of 1 cm with a common ruler.

    Rounding off is a means to simplify numbers and remove unnecessary details. This eases work. Where some accuracy is required, then you don't round off.
    why do we round up at 5 why not down ?
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  6. #6
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    I think it's just convention.
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  7. #7
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    Here;s my justification.


    When rounding a number, the critical digit can be any of ten digits:
    . . . \{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9\}

    It seems "fair" that half of them round-down and the other half round-up.

    . . . \underbrace{0,\:1,\:2,\:3,\:4,}_{\text{round down}}\:\underbrace{5,\:6,\:7,\:8,\:9}_{\text{roun  d up}}
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