What's 0 - -2^2 on your Calculator ?

Discussion in 'Community Discussion' started by OSMac, Oct 14, 2013.

  1. OSMac macrumors 65816

    Joined:
    Jun 14, 2010
    #1
    Try entering 0 - -2^2 on your calculator , most seem to give the wrong answer?

    What's calc do you have , what's the result ?
     
  2. wordoflife macrumors 604

    wordoflife

    Joined:
    Jul 6, 2009
    #2
    4 on my Ti-84 Plus SE

    But seriously, as strange as it sounds, your question is vague. Are you talking about 0 - (-2)^2 or 0 - -(2^2) or 0 (- -2)^2 , etc etc.

    You need to know how your calculator works before you can use it. Depending on what the question is asking, I can get the 'right' answer.
     
  3. Comeagain? macrumors 68020

    Comeagain?

    Joined:
    Feb 17, 2011
    Location:
    Spokane, WA
    #3
    The calculator is very strictly following order of operations as it knows them, whereas we are usually ignoring certain things. It's most likely giving you zero minus the opposite of 2 squared (4). Not zero minus negative two squared (-4).
     
  4. OSMac thread starter macrumors 65816

    Joined:
    Jun 14, 2010
    #4
    Even simpler what is... -2^2

    On a recent TI
    [negative key ] [2] [squared] gives -4 .

    On my old 80’s Sharp el506
    [2] [negative key] [squared] gives 4 as expected.

    Sure know how to use your calc, but what's the reasoning of new calcs?
    It seems the [negative] key does not enter a negative number,
    Instead it multiples a by -1... Forcing the use of brackets.
     
  5. OSMac, Oct 15, 2013
    Last edited: Oct 15, 2013

    OSMac thread starter macrumors 65816

    Joined:
    Jun 14, 2010
    #5
    [0] [minus] [2] [squared] makes sense to be -4

    But

    [0] [minus] [negative] [2] [squared] should also be -4

    Just look at the last entry in the display below,
    algebraic entry was suppose to improve things?
     

    Attached Files:

  6. Don't panic macrumors 603

    Don't panic

    Joined:
    Jan 30, 2004
    Location:
    having a drink at Milliways
    #6

    if you want the negative to be included in the power operation, you have to include it in parentheses:

    -2^2 = - (2^2) = -4
    (-2)^2= +4

    therefore
    0 - -2^2 = 0 - -(2^2) = 0 - -4 = 0 + 4 = 4
     
  7. OSMac thread starter macrumors 65816

    Joined:
    Jun 14, 2010
    #7
    The hp 50g is slightly better in algebraic mode,
    If [minus] [negative] keys are pressed in sequence the operator displayed changes to plus so its clear you need to use brackets but it still allows negative 2 squared to display an answer of -4.
     

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  8. Comeagain? macrumors 68020

    Comeagain?

    Joined:
    Feb 17, 2011
    Location:
    Spokane, WA
    #8
    [​IMG]

    That's what is going on as far as I can tell.
     

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