## Tuesday, January 17, 2012

### TI-36X PRO: Programming Bug Info (VIDEO)

In a previous post (link), I explained why the TI-36X PRO is a great calculator is you are taking the Fundamentals of Engineering or PE Exam. But it has one problem: a programming bug. Essentially, the bug is a display problem which only occurs when you try to display a mixed fraction involving pi, but still, any time your calculator is giving you wrong answers it is a serious problem.

I made a video to illustrate the bug, embedded below:

To check if your TI-36X PRO has the bug, first make sure you are in MathPrint mode. You can check this by pressing $$mode$$ and scrolling down to the bottom of the list of options. Now, you need to tell the calculator to display answers in mixed fraction form. To do this, type $$1.75$$ into he command line, then press $$math$$ then $$1$$ then enter. You should see the result $$1\frac{3}{4}$$. Then type $$\pi12.5^2$$ into the command line. When you hit $$enter$$, you should receive the answer $$490.8738521$$. Now press the answer toggle button (it is directly above $$enter$$) and your calculator will display $$154\frac{\pi}{4}$$ if your calculator has the bug. The mathematically correct answer would either be $$\pi154\frac{1}{4}$$ or $$\frac{\pi654}{4}$$. Remember to clear the memory (hit $$on$$ and $$clear$$ at the same time) after you try this!

Overall, I’m still a fan of the calculator. To avoid the bug, I never try to convert anything to a mixed fraction. There are very few times where I ever need a mixed fraction anyway. You can get all the information you need in either decimal or improper fraction form. I actually used this calculator on the Fundamentals of Engineering Exam and I was very happy with it.

The Consumerist Article: http://consumerist.com/2011/09/this-texas-instruments-calculator-cant-calculate-correctly.html
Here is a video from MrTechLabs describing the same problem:

1. The answer is not wrong on the calculator it is telling you 156+pi/4 still just as it did with 1.75=1+3/4. This is not a bug it is just a misconception

1. No, 156+(pi/4)=156.785398... not 490.87385... which is the value we are trying to represent. The calculator's value is mathematically incorrect.

2. Okay, I'm a little confused. I just bought this calculator.. I did as you said to see if my calculator had the bug & the answer I got back was 156 π/4. Is this wrong? or right?

3. @rachel wrong indeed..the real value should be 490.8.jst think tis way,for solving (12.5^2)*pi ( 12.5^2 will be more than 144+ approximately ,which is multiplied by pi whose value is more than 3 so the real ans should be more than 450+ ie 490.8) our calculator is giving 156 pi/4=156.78..i hope ur confusion is nw cleared

4. The two correct answers should be pi*156-1/4 or (pi*625)/4

5. Oh, I get the problem. The calculator knows the number to be (156 and a fourth) of pi, but it displays 156 and pi over 4.

Mixed fractions are dumb anyway.

6. I just bought my TI36. I tried π12.5^2 and i got 154π/4. Then I hit ''on'' + ''clear''. Now after the memory cleared I'm getting 625π/4. Does it mean there is no more bug?

1. No. The bug is still there. You just have to refresh the bug by using math 1 at any time.

7. I too have gotten rid of the bug by holding down [on] and [clear] at the same time. Thanks!

8. "On+Clear" Seems to have cleared up the issue for me as well... Strange...