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> zero has many properties that other numbers do not In particular, zero is the additive identity [0] in almost all the "usual" number systems in which it appe
by j1vms 7y ago
> zero has many properties that other numbers do not
In particular, zero is the additive identity [0] in almost all the "usual" number systems in which it appears. That is roughly speaking, it is the only A such that X + A = X, for all X, where X and A are elements of the number system (e.g. field of real/complex numbers).
[0] https://en.wikipedia.org/wiki/Additive_identity https://en.wikipedia.org/wiki/Additive_identity
- jakobegger 7y agoIt's also the only real number that does not have an inverse element for multiplication (there is no number b such that (a * 0) * b = a)
- james_s_tayler 7y agoThe integers form a group under multiplication though and a key property of a group is that every element has an inverse. So how does the definition hold if there is nothing that could be considered an inverse for the number 0? Curious about this... I never thought about it before.
- ulrikrasmussen 7y agoYou are thinking of the multiplicative group of integers coprime to some integer n. That set by definition never includes 0.
- jacobolus 7y agoThe integers do not form a group under multiplication. As you noticed, the multiplicative inverse of any integer other than 1 or –1 is not an integer. You might be thinking of the rational numbers (excluding zero).
- james_s_tayler 7y agoWoops. You're right. Looks like I need to play Group or Not Group. https://youtu.be/qvx9TnK85bw https://youtu.be/qvx9TnK85bw But then even for addition what's the inverse of 0? -0?
- MrQuincle 7y agoIntegers form a monoid under multiplication. PS: A monoid in which each element has an inverse is a group.
- ZeikJT 7y ago1 is the only A such that X + A = X + 1 :D