# Calculator Malfunction Ti-36X Pro



## DLD PE (Oct 14, 2019)

I'm pretty sure Zach Stone recommend buying two calculators and bringing them to the exam.  At first I thought this was overkill, but now I know why he said it.

I took a timed 8-hour practice exam yesterday.  I had just started the afternoon portion when my calculator "froze".  I was using the "store" function and I don't remember if I hit the same button twice in succession or what I did to make it "freeze", but all of a sudden, none of the buttons worked.  I saw some little hourglass symbol in the display, something I had never seen before.  I couldn't even turn it off.  I thought, "if this was the real exam I'd be panicking."

Then I discovered the little "reset" button at the bottom of the back of the calculator.  That did the trick and I was back on track, losing maybe only a half a minute on time. 

I was doing ok, or so I thought.  I realized I was running into problems I really thought I knew how to do but wasn't getting any of the answer choices.  I discovered when I reset the calculator the modes were also reset to factory defaults, so when I was calculating complex numbers I was getting wrong answers.

Don't let this happen to you!  If you're only bringing one calculator, at least know how to reset it, bring a spare set of batteries and know what modes you're using so you can quickly set it back up if you have to go through this.

Here's what I have mine set to (when I press "Mode":

DEG, NORM, 3 (instead of FLOAT), r&lt;0 (instead of REAL), DEC, and MATHPRINT


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## txjennah PE (Oct 14, 2019)

I was so paranoid that I brought TWO backup calculators.  I'm glad that you had this issue now and not during the exam!


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## roy167 (Oct 14, 2019)

Some calculator may require little screw driver to pop open the cover to replace battery, not sure if exam would allow this as this may be considered as weapon. I replaced the batteries at home , took two calculators to the exam. Without calculator you fail the exam. Importance of calculator is right at par with ID. Without ID, you can't get in the exam hall. Without Calculator, you can't pass the exam.


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## DLD PE (Oct 14, 2019)

They allow the little screwdriver.  It's not a banned item the last time I checked.

I still think it's better to take a backup calculator.  Easier to whip it out and start using it versus spending time replacing batteries or resetting the calculator.


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## ChebyshevII PE PMP (Oct 14, 2019)

I took a screwdriver with me last year in WA state, they seemed to be ok with it. It’s more for the case where for whatever reason both your primary and backup calculator die during the exam.

On that note, i’d recommend installing fresh batteries before you go to the exam.


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## Zach Stone P.E. (Oct 14, 2019)

MEtoEE said:


> I'm pretty sure Zach Stone recommend buying two calculators and bringing them to the exam.  At first I thought this was overkill, but now I know why he said it.
> 
> I took a timed 8-hour practice exam yesterday.  I had just started the afternoon portion when my calculator "froze".  I was using the "store" function and I don't remember if I hit the same button twice in succession or what I did to make it "freeze", but all of a sudden, none of the buttons worked.  I saw some little hourglass symbol in the display, something I had never seen before.  I couldn't even turn it off.  I thought, "if this was the real exam I'd be panicking."
> 
> ...


About once a year I hear the same horror story on repeat. Someone walks into the exam room after spending four to six months really preparing and putting in the time. For some reason or another their calculator stops working and they did not bring a back up. They fail the exam. 

Calculators are $15-$20 on amazon. Compared to all the other expenses involved with taking the PE exam, it is cheap insurance! 

Get a back up.


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## DLD PE (Oct 14, 2019)

I did.  No need to take chances.


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## Ranger1316 (Oct 14, 2019)

Don't be like me and forget both calculators in the car either. That was the fastest I've sprinted in my life lol.


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## DLD PE (Oct 14, 2019)

I have a large book bag I carry several of my "go-to" references in.  It has a side pocket where I carry my calculator (soon to be 2 lol), pencil and ear plugs.  I make it a habit to carry them all in the same place every time I bring all my stuff to the library or work or wherever I take my timed practice exams.  I just make it a habit so I won't forget it.


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## LyceeFruit PE (Oct 14, 2019)

Don't forget to take out that pencil before you head into the exam though.


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## fyrfytr310 (Oct 14, 2019)

As @Zach Stone, P.E. says, it is cheap insurance to have a spare (or 2 if so inclined) just in case.

I took one personally but did not have to use it fortunately.  Now I have a backpack calculator and a desktop calculator so no real loss in $$$ anyway.


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## Sparky Bill PE (Oct 14, 2019)

Can anyone with experience please elaborate on when would be great ideas to use this "store" function on our TI-36X pro. I know that calculator like the back of my hand, but that seems to be a function I should be using but I can't seem to find a good reason when.


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## DLD PE (Oct 15, 2019)

I use it for MVA calculations all the time.  In my opinion it's faster and helps reduce chances for mistakes.

For example, to find the fault current you need the total MVA of a system.  I calculate 125 MVA for the transformer and 115.2 kVA for the line. After each calculation I store the numbers as X and Y.  Then to find the total MVA of the system I just press X*Y/(X+Y).  Takes less time versus re-typing a bunch of digits plus you'd be surprised how often you might make a mistake doing all that under pressure.

Anytime you have a problem where you know you're going to reuse a calculated value, it helps to use the store feature, especially when working with complex numbers.


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## DLD PE (Oct 15, 2019)

Here's an example straight out of the Graffeo practice exam #69 (the previous example I posted was from an Eng Pro Guides problem).  Before calculating the line impedence pick up value, Z=V/I, I need to find the primary voltage and current pick up values.  

Vpri = 1,000,000&lt;0, Ipri = 20,000&lt;-35.  That's a lot of buttons to "re-press" into the calculator to find Z.  

Try solving the problem both ways.  As soon as you calculate Vpri, hit "Sto-" then the button above once for "x" and hit enter.  Then for Ipri you hit "Sto-" then the button above twice for "y".  Then it's simply x/y then enter to get Z.  Try this for several different problems until you get the hang of it. 

I also like to keep the calculator in "mathprint" mode and make heavy use the "box divided by the box" button, the one right above the "7", if have a long fraction and I want to see all the numbers in front of me while I enter them.  

Hope this helps and proves useful!


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## Drewism (Oct 15, 2019)

I've always taken two calculators to the FE exam and the PE exam. I remember during my practice sessions I would calculate a really intensive problem using the "poly solve" function on the Ti-36X Pro. It ended up getting the hourglass symbol and taking some time to solve. So, I set it down and went to another calculator and proceeded while the other did its calculations. Definitely take two especially since they're not that expensive compared to other materials.


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## Toby-Wan (Nov 1, 2019)

My table partner's calculator died 5 minutes into her exam. Thankfully, someone who took @Zach Stone, P.E.'s advice was able to save the day! (via proctor, of course).


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## Zach Stone P.E. (Nov 4, 2019)

Toby-Wan said:


> My table partner's calculator died 5 minutes into her exam. Thankfully, someone who took @Zach Stone, P.E.'s advice was able to save the day! (via proctor, of course).


Best insurance there is. Calculators are about $20 on amazon and can be delivered to your door in a few days with prime.


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