And yes it has helped me eg. estimate things or whatever along the years – but of course it's not going to be some sort of magical mathematics trick where just by reversing the numbers it'll always make things easier to calculate in your head

[–] TAYRN@lemmy.world 4 points 1 year ago* (last edited 1 year ago) (1 children)

No, I think we all learned that multiplication is commutative in late elementary school, and obviously that's an important thing to know.

But I think the original post tried to make it out to be some magical mathematical trick, and I really don't understand that. Maybe I misunderstood the post.

Edit: wow, "commutative" is a really hard word to spell.

[–] hydroptic@sopuli.xyz 4 points 1 year ago (1 children)

Yeah I think this is more about how you interpreted it, because it doesn't look like others took it as being an absolute magic trick rule and neither did I.

The Panzer of the Lake didn't use the word "commutativity" (fuck that really is hard to spell), but it gave out some wisdom that applied that rule by saying that "percentages are reversible": if the reverse of a percentage would be easier to calculate, you can use it and get the same answer. If it's not easier, well, then you're screwed 😁 Oooooor depending on the situation you can use the a × b% = a × b / 100 commutativity trick:

7 × 8% = 0.56

7 × 8 / 100 = 0.56

[–] TAYRN@lemmy.world 4 points 1 year ago (1 children)

Oh, that is actually much more helpful. So, if you know your times tables, you can do percentages. You just have to use communitavatization.

Jokes aside, I really appreciate it. That made it much more easier to understand. Thank you.

[–] hydroptic@sopuli.xyz 2 points 1 year ago (1 children)

You're welcome! Glad I could give you an a-ha moment.

Having an intuitive feel for tricks like using the definition of operators or symbols to make your life (well, calculations at least) easier usually means that you either have to just be "naturally" talented at math which is really rare, or you've just had to grind grind grind math at eg. university, work or whatever. So unless someone was taught that above trick and they actually remember it from school, they might never come to think that "hmm % just means / 100 so that can make this easier to figure out in my head".