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Math Help - Multiples of 7 between 400&500

  1. #1
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    Multiples of 7 between 400&500

    I was doing a problem on Arithmetic progression where I have to find number of terms those are multiples of 7 between 400 & 500.

    I found that value of a term which is multiple of 7 can be generailzed by:
    400+(7n-1) [where n=1,2,3...][constructed this by using firs multiple 406]

    and no of terms was found by: 7n = 100 [since total 100 terms between 400&500]

    so n= 14 (approx.)

    This can also be done:
    400+(7n-1) <500
    by calculating n<14.43 which can be said n=14

    I wanna know are these methods right? Is there any general formula of multiples of any number??
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  2. #2
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    Dec 2008
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    Auckland, New Zealand
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    I don't know about any formula, but what you have done in this case is correct and has given you the correct answer.
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