https://zeta.one/viral-math/

I wrote a (very long) blog post about those viral math problems and am looking for feedback, especially from people who are not convinced that the problem is ambiguous.

It’s about a 30min read so thank you in advance if you really take the time to read it, but I think it’s worth it if you joined such discussions in the past, but I’m probably biased because I wrote it :)

  • Spacehooks@reddthat.com
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    1 year ago

    It seems Americans are taught pemdas and not bodas.

    I Looked up doing factorials and n! = n(n – 1) is used interchangeably with n! = n*(n – 1)

    So Americans will multiply anything first. This is why I put 6 ÷ ( n*(n – 1)) in excel to avoid confusion.

    • Echrichor@feddit.uk
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      1 year ago

      Americans use PEMDAS, in the UK we use BODMAS, and I assume other English speaking countries use one or the other, but there is no difference between them in terms of order of operations, because it’s:

      1. brackets (parenthesis)

      2. orders (exponentials)

      3. division & multiplication (multiplication & division), performed left to right

      4. addition & subtraction, performed left to right

      People who choose to divide or multiply first because of the acronym have just forgotten that they go together left to right.

    • I Looked up doing factorials and n! = n(n – 1) is used interchangeably with n! = n*(n – 1)

      Yeah, there’s a problem with some lazy textbook authors, which I talked about here. A term is defined as ab=(axb), and yet many textbooks lazily write it as ab=axb, which is fine if that’s the whole expression, but NOT fine if the expression is a/bc (a/(bxc) and a/bxc AREN’T the same thing!), and so we end up with people removing brackets prematurely and getting wrong answers. In other words, in your case, only n!=n(n – 1) and n!=(nx(n – 1)) can be used interchangeably.

    • kuneho@lemmy.world
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      1 year ago

      I Looked up doing factorials and n! = n(n – 1) is used interchangeably with n! = n*(n – 1)

      yeah, the way I have been taught is that either you put the multiplication sign there or not, it’s the exact same, there’s absolutely no difference in n(n-1) and n*(n-1). in the end, you treat it like the * sign is there and it’s just matter of convenience you can leave it off.