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I always see companies advertising their products as "700% effective " or "the product kills 900% germs". But percent means "out of hundred". So how can the percentage be more than 100 like 700% or 900%?

pro neon
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  • Are you sure it doesn't say something like: "The product kills 900% more germs"? – Eff Aug 03 '18 at 08:54
  • Yeah something like that. – pro neon Aug 03 '18 at 08:54
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    Some exact quotes may help. In some contexts, more than 100% would not make sense but in others it might. It might be more of a question of English than of maths. It depends on what 100% represents: some absolute limit that cannot be exceeded or just an arbitrary reference point which could be. – badjohn Aug 03 '18 at 09:10

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700% would mean that it's 7 times as effective than a previous product or another company's product.

Meeta Jo
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    7 times more effective, or 7 times as effective? :p – Bart Michels Aug 03 '18 at 08:55
  • thanks, just changed it – Meeta Jo Aug 03 '18 at 08:56
  • Yeah. But isn't that wrong? Since for comparison mostly companies say "7X". Isn't using percentage in these cases wrong? – pro neon Aug 03 '18 at 08:57
  • @proneon True, almost everybody says 7X. I'm just nitpicking. By contrast, I do not recommend saying 100% more effective when what you mean is that there is no difference ;) (My comments are irrelevant to your question. Don't let them confuse you.) – Bart Michels Aug 03 '18 at 09:02
  • Thanks for helping. – pro neon Aug 03 '18 at 09:03
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    @proneon No, it's not really wrong. To say that something is $7$ times better is exactly the same, mathematically, as saying $700%$ better. Because $% = 1/100$ we have that $700% = 700\times\frac{1}{100} = 7.$ Perhaps linguistically it may be confusing, though. – Eff Aug 03 '18 at 10:20