Easy Log function on a TI-89 Titanium

I know this is outside of the normal topics discussed on this site but I felt a serious need inform others about hidden functionality on the Texas Instruments TI-89.

Recently in my math class I was required to use the log function on my TI-89 Titanium. I couldn’t find it except by using the catalog. I read the manual and searched on the internet, I couldn’t find a better method, I in fact fount a lot of worse methods. So sitting in class I started pushing the alternate function keys and pressing all the keys without their alternate function listed. The calculator does in fact have a quick key for the Log function. Diamond & 7


84 Responses to “Easy Log function on a TI-89 Titanium”

  1. 1 David Grillot March 29, 2009 at 5:50 pm

    Just one more example of the cryptic input for the TI-89. Shame on Texas Instruments.

  2. 7 Victor August 19, 2009 at 6:17 pm

    Thank you sooooo much. You do not believe how troubling this was for me.

  3. 8 Tadas September 15, 2009 at 7:17 pm

    Awesome find! Been searching online for this shortcut, glad someone found an easier way than scrolling through the catalog

  4. 9 Anish October 7, 2009 at 9:01 am

    I pressed diamond & 7 for log function. But I am not able to get it in TI 89. when I checked it using diamond EE, 7 has been assigned to some other KBDPRGM. How can I set it to log?

  5. 12 great find! January 27, 2010 at 8:16 pm

    i am very thankful you found this! To get by this problem i found the following instructions that have worked for me for a while, it actually is pretty useful for a quick log function for non base 10 stuff: make a function that does the log base anything of anything. try this: define Logg(a,b)=ln(b)/ln(a) or you could do ln(b)/ln(a)-> Logg(a,b) (ps the ‘->’ is the store button on your calculator. I think define is f4 or something, if you can’t find it look in your catalogue)

  6. 13 Randi March 26, 2010 at 9:07 am

    Thank you so much Diamond and 7 is just what I needed to know!!!

  7. 14 Mark April 28, 2010 at 5:16 pm

    Thank you!!!!!!! This was driving me crazy!!!

  8. 15 Melissa April 29, 2010 at 5:08 am

    I knew there had to be another way!!!! geeeeeeez!!!! lol! Thank you!!!!

  9. 16 Estevan August 4, 2010 at 9:50 am

    God bless you, sir.

  10. 18 Dan November 14, 2010 at 12:17 pm

    Thanks man… I was getting so tired of using ln(?)/ln(10) over and over again.

  11. 19 Daye November 22, 2010 at 11:19 am

    You Rock!! Thank you!! I was trying to figure out how to do these problems!!

  12. 20 Matthew December 12, 2010 at 4:32 pm

    Bless you sir, bless you!

  13. 21 Courtney February 21, 2011 at 3:58 pm

    thanks a lot!!!

  14. 23 Svetlana March 30, 2011 at 12:27 pm

    Thank you soooo much! God bless you!

  15. 24 STRESSED STUDENT April 16, 2011 at 11:34 pm


  16. 25 TPenn April 18, 2011 at 7:59 pm

    THANK YOU SO MUCH FOR THIS! I was typing in LOG with the alpha key rather than go through the catalog. This makes my life so much easier as I needed the Log to find pH in chem class.

  17. 26 Di April 20, 2011 at 2:22 pm

    God Bless you you help me so much !!!THANKS A LOTTTTTTTTTTTTTTTTTTTT

  18. 27 JAY May 7, 2011 at 8:03 pm

    THANK YOU!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  19. 28 vicky September 8, 2011 at 8:49 am

    Thanks!!! it has releived alot of headaches!

  20. 29 Sam October 8, 2011 at 9:21 pm

    Thank you! I’ve have had my TI-89 Titanium for six years and had no idea you can get log without having to go into the catalog.

  21. 30 viviane November 5, 2011 at 7:14 pm

    It really works. You’ve saved my day. Thank you so much for sharing, we really apreciate your kindness.

  22. 31 Rei November 5, 2011 at 10:23 pm

    This is not so on the TI-89 just the TI-89 Titanium it would seem.

  23. 32 ossie apalategui November 7, 2011 at 7:01 pm

    i need help how do i type in Log1200=x on my ti 89 titanium???

  24. 33 Jessica November 16, 2011 at 7:53 pm

    This was so helpful! I scavenged through so many websites and this saved me the day before my midterm. THANKYOOOOU!

  25. 34 Amanda December 6, 2011 at 9:11 am

    THANK YOU for posting this! My brain hurt trying to find this in the catalog each time.

  26. 35 Rene December 13, 2011 at 10:14 pm

    I happen to press diamond 7 and it does not work for me. Help?

  27. 36 Cheezor January 25, 2012 at 3:23 pm

    Yo thanks this shit is beast fuck yeah you’re so sick the man bromanseph

    fuck that shit was pissin me so off but saved day super cool man

  28. 37 Will Klatt February 8, 2012 at 6:18 pm

    To calculate log base 2 of a number type log(number,2)

  29. 39 BAYMAN February 9, 2012 at 4:05 pm


  30. 42 kong April 10, 2012 at 2:08 am

    ohhh wow! thanks a bunch! was raging last night just to find this button

  31. 43 itznu May 11, 2012 at 12:37 pm

    most useful blog on the internet award goes to…..*opens envelope suspensefully* You! thanks for posting 😀

  32. 44 Ro Chelle July 19, 2012 at 8:01 am

    press (diamond) EE, there are shortcuts for the TI89. ie: (diamond then division key for factorial) (can’t live without that one!). diamond EE will bring you to the variety of commonly or not so commonly used shortcuts. they seem to be interchangeable between the two 89’s. both have a menu under the same (diamond) EE. diamond 7, however, is the titanium feature. check the individual menus

  33. 46 Amraa August 2, 2012 at 7:55 pm

    you just saved my life good sir.

  34. 47 RcBoy24 September 4, 2012 at 8:28 pm


  35. 48 Personalmap September 17, 2012 at 6:25 am

    God bless you for sharing this! I bought this new Titanium a day before my Math test (not a very smart move) and I was trying to figure it out… Thank you! thank you!

  36. 49 Felicity October 25, 2012 at 3:02 pm


  37. 50 Ziggy November 5, 2012 at 10:11 am

    Oh lordie thank you! I was falling behind in class because I couldn’t find this function for homework

  38. 51 beburr44 January 12, 2013 at 7:35 am

    I love you so much, WTF Ti morons

  39. 52 Lola February 20, 2013 at 1:12 pm

    I have a ti-89 titanium and diamond 7 doesn’t work on mine! Please help!

    • 53 Will February 20, 2013 at 2:37 pm

      Press [Diamond] and then [EE] to see a full layout of keys that are used with the diamond key. It should be on there. On my TI-89 titanium the [Diamond] key then the [7] key brings up log(

  40. 54 kitty kat March 12, 2013 at 4:25 pm

    this is beautiful omg thank you so much

  41. 55 Saras March 27, 2013 at 2:13 pm

    I jizzed in my pants! Thanks!

  42. 56 Vince Gonzales April 10, 2013 at 12:59 pm

    What a time-saver! Thanks a lot, you rock!

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    Keep up the good work! You understand, many persons are hunting round for this info, you can help them greatly.

  44. 58 cacawuate July 8, 2013 at 10:00 pm

    Thank you so much!! you are freaking awesome!!!!

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  48. 62 Fermin September 10, 2013 at 1:48 pm

    I used too be able to find good info from your content.

  49. 63 dari September 24, 2013 at 8:13 pm

    omg i love u!!

  50. 64 Jjackson October 11, 2013 at 8:50 am

    hallelujah! Thanx!

  51. 65 geo November 4, 2013 at 8:44 pm

    thank you so much ❤

  52. 66 marie p. December 5, 2013 at 12:27 am

    its very frustrating to buy an expensive calculate like the ti-89 and can’t really work with it in class because the instruction to navigate the product is only located on line. with the amount of money spent on this item it should have some kind of basic instruction. didn’t figure out the online business until toward the end of my semester. my math class is not based on using this calculator and computer product in class. it’s based on using only this product and knowing how to navigate it to solving problems such as the logarithms function which is not explain how to find the key functions.

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  54. 70 MIRANDA February 16, 2014 at 9:49 pm


  55. 71 David April 14, 2014 at 5:37 pm

    I was staring at my calculator thinking where the **** is the log key thank you so much for posting

  56. 74 Laura McCree November 18, 2014 at 11:11 pm

    thank you thank you thank you thank you

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  58. 76 andrew February 23, 2015 at 10:32 pm

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  59. 77 Johnson April 14, 2015 at 6:05 pm

    Someone should slob your knob for this. Not me, but someone. Good lord what a helpful fucking thing to have discovered.

  60. 78 PS4 Gamer May 29, 2015 at 6:32 pm

    When I enter log(15) on my calculator, it gives me log(15) as an answer. How do I get the actual answer?

  61. 79 Crédit nouveau départ June 24, 2015 at 12:31 am

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  62. 80 JerryT July 4, 2015 at 8:18 am

    I have spent soooo much time trying to figure this out, thank you so very much. Not sure why it should have been this difficult figure out. If you’re working with Logs, your not a dummy, shame on TI for not making this clear

  63. 81 TI-89 user September 16, 2015 at 2:36 pm

    This is awesome that the OP posted in 2009, and people like me are still finding this in 2015. I’m sure you’ve moved on, OP, but thank you, thank you, thank you!

  64. 82 TI-89 March 22, 2017 at 12:28 am

    thank youso much!!!

  65. 83 Alicia October 17, 2018 at 11:04 am

    THANK YOU!!!!! Years after you posted this and I needed it so much today! Thank you, thank you!

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