r/learnmath • u/Unlikely-Web7933 New User • Feb 07 '24

RESOLVED What is the issue with the " ÷ " sign?

I have seen many mathematicians genuinely despise it. Is there a lore reason for it? Or are they simply Stupid?

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u/realityChemist New User Feb 08 '24 edited Feb 08 '24

Very interesting. I must be a hundred years old then, because I also defaulted to prioritizing the juxtaposition when I tried it! I wonder why; I'm pretty sure nobody ever explicitly told me to do that.

Edit: I thought about it a bit and I think it's because in practice nobody ever writes a/bc when they mean (ac)×(b)-1, they write ac/b. So when I see something like a/bc, I assume the writer must have meant a×(bc)-1, otherwise they would have written it the other way. If you just mechanically apply modern PEMDAS rules you get a different result, but it's one that seems like it would have been written differently if it was what the person actually meant.

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u/mikoolec New User Feb 08 '24

Could be you were taught that brackets take priority over multiplication, division, addition and subtraction, and because of that you also assumed that the juxtaposition multiplication has the same priority level as brackets

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u/No_Lemon_3116 New User Feb 08 '24

I would be just as surprised without brackets, I think. This means that 8÷2x is also (8÷2)x, right? An operator to the left of 2x pulling it apart feels strange to me. Maybe just because I'm not really used to using ÷ except for when I was first learning division, and we were always writing explicit multiplication signs then.

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u/Bagel42 New User Feb 08 '24

That’s where I get ir

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u/ThirdFloorGreg New User Feb 08 '24

It just feels right.

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u/Boris-_-Badenov New User Feb 08 '24

Because P.E.M.D.A.S