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Posted

To cut a long story short, as they say :rolleyes: , I'm throwing together a kind of "pub quiz" for some friends - it's maths based. The idea is you have to find sums for certain numbers but you're not allowed to use some basic maths operations. Now I just need clarification on something: If you weren't allowed to use subtraction when you're coming up with sums would you still be allowed to use negative numbers? (e.g. -4 + 5) I've never been sure whether, when you do a simple sum like "5 -3" you're doing "+5 - +3" or what you're actually doing is "+5 -3" I've never been sure because you can do sums like " -5 - -3" as well

 

 

Clarification appreciated! :lol:

Posted (edited)

You could say that there is no such thing as subtraction, but there is always an additive inverse and zero is the additive identity.

 

So, for all [math]a \in \mathbb{R} \:\: \exists \:\: (-a) \in \mathbb{R} [/math] such that [math]a +(-a) = 0 [/math].

Edited by ajb
  • 2 weeks later...
Posted

You could say that there is no such thing as subtraction, but there is always an additive inverse and zero is the additive identity.

 

So, for all [math]a \in \mathbb{R} \:\: \exists \:\: (-a) \in \mathbb{R} [/math] such that [math]a +(-a) = 0 [/math].

 

 

This is :1) absolutely true and, 2) unlikely to be fully appreciated in the environment of your average pub, by your average pub denizen..

Posted

This is :1) absolutely true and, 2) unlikely to be fully appreciated in the environment of your average pub, by your average pub denizen..

 

 

I am not sure any pub quiz about mathematics will be fully appreciated in just about any pub. Unless it is very close to a mathematics department. :rolleyes:

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