The "Hijacked Thread" Thread

[Arcadia]

Mmmm.... maybe not the spamming, okay? Kind of a no no, so I've deleted it. K?

[johnspec]

k

[johnspec]

well my troll faces are off the chart again

[johnspec]

so how much are we hijacking this thread again?

[SherlockedCAMPer]

That moment when the radio station you were practically raised on plays a 2'fer Tuesday (2 songs from the same artist back-to-back) of your favorite artist with both songs being favorites off the current album & the 2nd song isn't even technically a single and you tweet the artist about it & he responds happily surprised. Me right now when I should be trying to sleep:      :D   (Now to try to get some sleep)

[J.P.]

Yep-p. I feel your pain. :P

[johnspec]

i don't feel your pain CAMPer but i do feel like i want to sing serenity.

[SherlockedCAMPer]

That moment when a friend (who's half your age) shares a math equation on facebook & you have to remind his other friends around that same age that the mnemonic of PEMDAS does not mean that multiplication (or addition) is always before division (or subtraction) but the order of the 2 is based on which comes first in the equation when going from left to right when horizontal or top to bottom when written vertically (Something I learned in 4th grade nearly 30 years ago).  So the equation 6÷2(2+1)= 9 not 1 and any calculator that allows you to enter the equation as written before clicking the equal sign will attest to that.  It may have been over 20 years since I had math but I still remember it especially since I homeschool johnspec and get great reviews every day he does his math.  Speaking of which, need to get him to do his school work for the day.

[Carol the Dabbler]

... So the equation 6÷2(2+1)= 9 not 1

I would be inclined to say 1 myself, and I majored in math. However, we didn't tend to use a divide sign. We would put the one number (or expression) over the other one, which is a whole lot less confusing (but a whole lot harder to do on a computer -- and apparently impossible to do on a cell phone, even when using the so-called "full" version of the forum, which is where I'm at right now).

[SherlockedCAMPer]

 

... So the equation 6÷2(2+1)= 9 not 1

I would be inclined to say 1 myself, and I majored in math. However, we didn't tend to use a divide sign. We would put the one number (or expression) over the other one, which is a whole lot less confusing (but a whole lot harder to do on a computer -- and apparently impossible to do on a cell phone, even when using the so-called "full" version of the forum, which is where I'm at right now).

 

 

Most often the equation likely would be written 6/2(2+1)= when in the horizontal mode.

 

Would vertical looks something like:

 

6

/2

*(2

+1)

-----

 

when written out? I'm not even sure how parentheses are done vertically as everything was horizontal by the time I got to that point.

[Caya]

Well you can fudge it with underline, subscript and superscript. Like:

 

⁶  _{(2+1) =}

²

 

but then you can no longer argue about the result because it's clear now. :P

[J.P.]

To me it would be 1 too, because what I learned brackets > multiplication > division > addition > subtraction

 

Isn't

⁶   _{a substitute for (6 ÷ 2) and not just 6 ÷ 2?}

²

[Arcadia]

I didn't understand a word of any of that.

[SherlockedCAMPer]

I'm the odd sort who is quite analytical and quite creative so I, for the most part, got math even though I hated it and enjoyed art even though I haven't had a hands on art class since I was 14.

[Van Buren Supernova]

I understand every word but on its own. :p

 

 

 

P.S Actually I think it's 9.

Order of operation PEMDAS or BODMAS put substraction and addition as equal and multiplication and division as equal.

When there is two equal operations the order would then be done from left to right.

 

6:2(2+1)

= 6:2(3)

= 3(3)

= 9

[Carol the Dabbler]

Well you can fudge it with underline, subscript and superscript. Like:

 

⁶  _{(2+1) =}

²

 

but then you can no longer argue about the result because it's clear now. :P

 

Precisely!  Or one could write

 

.  . 6 .  .

2 (2+1)

 

(ignoring the extraneous dots, which are there merely so I could underline more than just the 6)

which is just as clear, but does equal 1.

 

But if it's possible to do any of that on a cell phone, I haven't yet figured out how!

[Caya]

You could, but unless I'm mistaken (which I freely admit is entirely possible)

 

 So the equation 6÷2(2+1)= 9 not 1 and any calculator that allows you to enter the equation as written before clicking the equal sign will attest to that.

 

is correct because, like she said, no calculator will interpret the bracket part as belonging to the lower part of the fraction, unless you type it like, 6÷(2(2+1))= with two extra brackets.

[Carol the Dabbler]

So now we're letting calculators decide what's proper math?  Somebody designed those calculators, you know -- what if they were wrong?  Are we going to change the way things have been done for hundreds of years just because somebody can't figure out how to make a calculator work that way? 

 

 

*sigh*  Probably we are.

[J.P.]

Well, I actually thought that math is the only thing that's ALWAYS the same...

[Caya]

Whoever designed and programmed those TI gizmos knows waaaaaaaaaay more about math than me - I always feel when using a Voyage model that I'm boring the poor machine to death, since it can solve calculus problems I tend to run away from and has plenty of functions the purpose of which I can only guess at. :D So when in doubt, I'm with the calculators.

 

eta: Okay, I decided to follow through on that whole "go ask google for someone who knows more about mathematics than you" concept, so take it away, the web's most extensive mathematics resource:

 

 

The diagonal slash "/" used as the bar between numerator and denominator of an in-line fraction (Bringhurst 1997, p. 284). The solidus is also called a diagonal.

Special care is needed when interpreting the meaning of a solidus in in-line math because of the notational ambiguity in expressions such as a/bc. Whereas in many textbooks, "a/bc" is intended to denote a/(bc), taken literally or evaluated in a symbolic mathematics languages such as the Wolfram Language, it means (a/b)*c. For clarity, parentheses should therefore always be used when delineating compound denominators.

Common examples of failure to parenthesize include E/kT (where E is energy, k is Boltzmann's constant, and T is temperature; Arfken 1985, p. 950), ... [more examples but I'm too lazy to dig up greek letters, go look at the link if you want to read them :P]

 

 

So it turns out everyone is right! If I understood that correctly, Carol is right in that, while strictly speaking the 2*(2+1) part should be in parentheses for it to be read as a compound determinator, it can be read as such, so either 9 or 1 would be possible answers. However, since the advent of calculators, who as of yet cannot guess as to whether or not this was meant as a compound, made a clearer syntax necessary; taken in such a context 9 is the only correct answer. So that's that - everyone had a good point, nobody was wrong and I hereby award all participants ten points to their Hogwarts house for mathematical fortitude!

 

[Carol the Dabbler]

So how come nobody makes a solar-powered reverse-Polish calculator?  Preferably one that doesn't look like the instrument panel of a 747?

 

I do see some virtual ones for Android phones.  Might download one of those, if any of them are usable off-line.

 

[Caya]

Should work offline, especially the ad-less ones - the app I use does, at least (not RPN, though, I have to admit I never got used to those). Of course, your cell phone isn't solar powered either. ;)

 

Does anyone but Hewlett Packard even make them anymore? Maybe mail HP and ask if there is one in planning. Not sure if there's much of a market for one, though, since the people who use Reverse Polish Notation tend to be the people who need calculators with, like you said, so many functions that they resemble an instrument panel, and that might use more juice than a small solar strip can provide.

[Carol the Dabbler]

I personally like RPN even for regular arithmetic, though a reliable memory calculator would serve about as well, I suppose.  I tend to find myself with the results of one calculation sitting on my calculator, and then needing to (for example) multiply it by the results of another calculation that I haven't yet, umm, calculated.  Or more often, I need to divide my calculated number INTO some number.  Yeah, memory would do it -- anywhere to park the intermediate result.  And/or an inversion function, which some fairly simple calculators do have.  A stack would be even better, of course, more flexible.

 

I've never trusted memory calculators, though.  Back before I gave up on using the memory function, they tended to malfunction just as I was ready to retrieve the saved value.  But maybe they're more reliable nowadays.

[Caya]

Modern calculators got your back on that particular problem, actually. The one I use most is the TI-36X, and like all modern TIs he got this nifty toggle wheel to the right (the silver thingie in the pic). It has many uses, like realizing twelve figures in that you mistyped the third one, and pushing it to go back for corrections instead of starting over, but the main function is that you can "grab" former calculations and results of these. So, to stay with the amazon pic, if you now needed to multiply 156 with 1.8288, you could grab the first one, hit multiply, then grab the second one. No need for putting it into memory (though the function is still there), you can always see what you're doing and it keeps the calculations you made even when turning it off, unless you use the reset button. I love my TI to bits, in case you haven't noticed already. :lol:

[Arcadia]

?????