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calculating percentage of percentage

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    calculating percentage of percentage

    How does one get "X" in excel from the formula 100=X-(X*21%)-(X*2.7%) ?

    Background: Credit cards take a percentage of the VAT inclusive amount. I would like this credit card cost to be automatically included in total VAT inclusive cost.

    For example, VAT is 21% and credit card fee is 2.7% on the total VAT inclusive amount. A theoretical VAT inclusive amount of 121 would have a credit card cost of 3.267 and a VAT cost of 21, so the net amount is not 100 but 96.733

    What would the VAT inclusive amount need to be to have a net amount of 100? And how does one put this in an excel formula?

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    Re: calculating percentage of percentage

    100=X-(X*21%)-(X*2.7%)
    Convert percentage to decimals:
    100=X-(X*0.21)-(X*0.027)
    Divide both side by X
    100/X=X/X-(x/x*0.21)-(x/x*0.027)=1-0.21-0.027
    Multiply both sides by x, then divide both sides by (1-0.21-0.027)
    X=100/(1-0.21-0.027)

    I think.

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    Re: calculating percentage of percentage

    "Divide both side by X" (x<>0)

    Regards
    Click * below if this answer helped

    Advanced Excel Techniques: http://excelxor.com/

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    Re: calculating percentage of percentage

    Ha

    100=X-(X*21%)-(X*2.7%)
    Convert percentage to decimals:
    100=X-(X*0.21)-(X*0.027)
    Factorise right side by X:
    10=X*(1-0.21-0.027)
    Divide both side by (1-0.21-0.027):
    X=100/(1-0.21-0.027)

    Better?

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    Re: calculating percentage of percentage

    Much better!

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    Re: calculating percentage of percentage

    Quote Originally Posted by yudlugar View Post
    Ha

    100=X-(X*21%)-(X*2.7%)
    Convert percentage to decimals:
    100=X-(X*0.21)-(X*0.027)
    Factorise right side by X:
    10=X*(1-0.21-0.027)
    Divide both side by (1-0.21-0.027):
    X=100/(1-0.21-0.027)

    Better?
    Sometimes life is so, so simple one doesn't see it and needs to be told. Thank you!!!

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    Re: calculating percentage of percentage

    I'd argue that the other one is valid when x=0 also though, as it would give you 0/0 which is possible

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    Re: calculating percentage of percentage

    Haha!

    So you claim - mathematicians have been debating the true definition of 0/0 for centuries!

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    Re: calculating percentage of percentage

    I like the:
    0/0=y
    therefore
    0*y=0
    therefore y can be any number
    arguement...

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    Re: calculating percentage of percentage

    Yes! A classic Christmas Cracker teaser for budding young mathematicians everywhere!

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