To cut a long story short, as they say , 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!

To be blunt - if you can be confused by your own rules then I think you may start some sort of riot!

To be blunt - if you can be confused by your own rules then I think you may start some sort of riot!

 

 

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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 September 1, 201114 yr by ajb

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..

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.