Science Memes

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[–] MotoAsh@piefed.social 4 points 9 months ago (2 children)

True, but as with many things, something has to be the rule for processing it. For many teachers as I've heard, order of appearance is 'the rule' when commutative properties apply. ... at least until algebra demands simplification, but that's a different topic.

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[–] SpaceCadet@feddit.nl 5 points 9 months ago (2 children)

something has to be the rule for processing it

Well the rule is: any order goes. Summation is commutative.

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[–] MotoAsh@piefed.social 4 points 9 months ago*

No, you completely misunderstood my point. My point is not to describe all valid interpretations of the commutative property, but the one most slow kids will hear.

OFC the actual rule is the order doesn't matter, but kids that don't pick up on the nuance of the commutative property will still remember, "order of appearance is fine".

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[–] Quatlicopatlix@feddit.org 2 points 9 months ago

Yes thank you! If you have a sum it is really great to order it in a way that makes it better to ad in your head and i think that lots of people do that without thinking about it. X=2+3+1+6+2+4+7+5 X=2+3+5+4+6+7+1+2 X=5+5 + 10 +7+1+2 X=10 + 10 + 7+3 X=10 + 10 + 10

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[–] SmartmanApps@programming.dev 0 points 8 months ago

order of appearance is ‘the rule’ when commutative properties apply

That's because students often make mistakes with signs when they do it in a different order, so we tell them to stick to left to right

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[–] kuberoot@discuss.tchncs.de -1 points 9 months ago (2 children)

If you have a bunch of unparenthesized addition and subtraction, left to right doesn't matter.

Right, because 1-2-3=3-2-1.

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[–] howrar@lemmy.ca 2 points 9 months ago (1 child)

You flipped the sign on the 3 and 1.

hideshow 2 child comments

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[–] kuberoot@discuss.tchncs.de -1 points 9 months ago (2 children)

I did not flip any signs, merely reversed the order in which the operations are written out. If you read the right side from right to left, it has the same meaning as the left side from left to right.

Hell, the convention that the sign is on the left is also just a convention, as is the idea that the smallest digit is on the right (which should be a familiar issue to programmers, if you look up big endian vs little endian)

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[–] howrar@lemmy.ca 2 points 9 months ago*

If that's your idea of reversing the order, then you're not talking about the same thing as SpaceCadet@feddit.nl. They're talking about the order of operations and the associativity/commutativity property. You're talking about the order of the symbols.