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Anonymous Posted on Nov 07, 2011

How to fix error mesage on TI-30Xa. Every time I press LOG an error sign comes up. how do i fix this?

  • 2 more comments 
  • kakima Nov 07, 2011

    Do you have a positive number in the display in when you press the LOG button? The LOG function operates on the number or expression in the display, and zero is not a valid argument.

  • Anonymous Nov 07, 2011

    DO i need to press the number first and then LOG, not just LOG itself, also how would i do negative LOG?

  • Anonymous Nov 07, 2011

    When i press just The LOG button it says error.

  • Anonymous Nov 07, 2011

    That was really helpful thanks. Also, how would I take a number and go to the power of .. like 10 to power of 6? Or for example take the -log10 of (7*10^5)

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2 Answers

kakima

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  • Posted on Nov 07, 2011
kakima
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To take the log of a number, enter the number then press the LOG button, then the =. To take the log of a negative number, enter the negative number using the +/- key just to the right of the decimal point. To calculate the negative of a log, calculate the log and then negate it using +/-. To calculate the antilog (inverse logarithm), press 2nd then LOG.

Bear in mind that LOG is the common (base-10) logarithm. For the natural (base-e) logarithm, use the LN key to its right.

  • 2 more comments 
  • kakima Nov 07, 2011

    If you just want to enter a power of ten, you can use the EE key just above the 7 key. For example, to enter ten to the fifth, press 1 EE 5.

    If you need to raise 10 to a possibly non-integer power, you can use the 10^x function (2nd LOG) since this is simply the common antilog.

    To calculate -log10(7*10^5) (negative log of 7*10^5), press
    7 EE 5 LOG = +/-

  • Anonymous Nov 07, 2011

    okay, but I still am not getting the right anwser. If i need to solve 14+log10 (7*10-5) how would i put that in my calculator?

  • Anonymous Nov 07, 2011

    I meant 14+log10 (7*10^-5)

  • kakima Nov 07, 2011

    1 4 + 7 EE 5 +/- LOG =

    I get about 9.85

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  • Posted on Aug 29, 2015
Jeremiah Krouse
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When I try to use my second function it keeps saying error.

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Related Questions:

0helpful
1answer

Hi, how do i calculate log^-1 on my ti-30xa? for example, in order to calculate log^-1(-2), what do i do? thank you.

The inverse of the common log function is the power function with base 10 (10^). It shares the same physical key as the log. You acees the function by pressing [2nd] [log]
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When I go to use the 'log' button on TI 30XA I do not come up with the same answer as in my course book (for the examples) No real instructions on logs in the little instruction book. Have tried...

You calculate the pH with the relation
pH=-log(c) where c is the value of concentration in mol/L.
ex: c[H+]= 3.57x10^(-6)
pH: (-) [LOG] 3.57 [2nd][EE] [(-)] 6 [ ) ]
Here you have 2 change sign key press [(-)]

If you have the pH, and want to calculate the concentration that yields that value of the pH you proceed as follows
c= 10^(-pH)
Ex pH=8.23
c: [2nd][LOG] [(-) 8.23 [)]

General shortcut.
If concentration is of the form c[H+]= 1*10^(-a) where a is an integer between 0 and 14, the pH is equal to the positive value of exponent.

Ex:c[H+]=1x10^(-5) Mol/L then the pH is just the positive value of the exponent, ie 5 because pH=-log(1.x10^-5) =- log1 -log(10^-5)=0 -(-5)=5
Above I use the rule log(axb)=log(a)+log(b) , the rule log(a^b) = b*log(a)and the facts that log(1)=0 and log(10)=1, the last being true if log stands for log in base 10.
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How do you find the log of 9.01 using TI 30xA calculator?

To calculate the common (base 10) log of 9.01, press 9 . 0 1 LOG =
To calculate the natural (base 3) log of 9.01, press 9 . 0 1 LN =

Both the LOG and LN keys are on the top row of the keyboard.
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I am trying to figure out how to enter negative logs into the TI-30XA. I have a chemistry exam on Tuesday and we need to be able to do problems with the negative log and I can't seem to find any...

Use the +- key to the right of the decimal point to enter negative values and to change the sign of an existing value. For your sample:
2 EE +- 3 LOG +- =
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How would I calculate -log(6.2 x 10^-8) on my TI- 30XA

6 . 2 EE +- 8 LOG +- =

EE is the Enter Exponent key, just above the 7 key. +- is the Change Sign key, to the right of the decimal point key.
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How do i make the log button negative?

Enter the number, then press the LOG button. Once result is displyed press the change sign key. If result is positive, it will become negative. If result is negative it will become positive. The Change sign key is the one with + -, located between the . and the = on the bottom row of keys.
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How to perform log and - log function

To use the log function you press the [LOG] key in the middle of the first row of keys.
To use it.
Enter the number the log of which you want to calculate (must be positive)
Press the [LOG] key
Result is displayed.

Ex log(33.54)
33.54 [LOG] result is 1.5255

Once a logarithm has been calculated, use the [+/-] key, the change sign key located between the [.] and the [=] keys, on the bottom row of keys. You must press the change sign after you have calculated the logarithm.
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How do i find the negative log on a TI-30Xa

Hi,

Ex: calculate -log(15.32)
  1. Calculate the log 15.32 [LOG] [=] result 1.185258765
  2. Then press the change sign key (-) result -1.185258765
You can also try 15.32 [LOG] (-) [=]. Try to veriufy it on your calculator.

Here is a picture of the change signd677d4e.jpg
Hope it helps
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Antilog in chemistry problem

pH is minus (log to base 10) of the hydrogen ion activity of an aqueous solution, or (log to base 10) of (1/hydrogen ion activity)

To get the inverse log, i.e the hydrogen ion activity corresponding to a specified pH, simply enter the pH value and press

2nd
LOG
1/x

Answer 0.001
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