HP 15C Scientific Calculator

HP originally created this app and it is based on the original calculator ROM. I still have my old 15C and did not hesitate to purchase this app when it came out at a far higher price than most other calculator apps on the Play store. After almost 40 years, this calculator still holds its own for quick, easy, and accurate operation, and the interface works as well with touch as it did with the tactile buttons (which have never worn out). This is an old-school Reverse Polish Notation (RPN) calculator. If you love to have full control over your computations and in exactly what order things are done, with an eye on precision or the effects of rounding, and the thought of not having to input parenthesis brings joy to your soul, this may become the best calculator experience you've ever had. There are newer, graphic calculators out, but for sheer number crunching and fast input, nothing beats the old XYZT RPN stack that the 15C was among the last of HP's calculators to use. (Newer models had much larger stacks which made calculations with constants much more awkward if you are familiar with how the 4-element stack works). Because you control the operator precedence explicitly, It helps you develop skills for recognizing the innermost parts of equations quickly, even very complicated ones. Those skills have helped me do some incredible performance optimizations in work otherwise unrelated to this calculator. Matrix operations are simple and extremely fast, and there's a crib sheet for advanced but slightly cryptic operations on the back of the physical calculator that they've duplicated in the app with a simple press of the menu button. It also includes a PDF of the original owner's manual, which includes an RPN primer as well as some high quality tutorials on algebra, matrix algebra, and other areas that can help reinforce material currently being learned in school or just refresh fading memories. Plus it's searchable and in full color. RPN does have a learning curve, so if you're someone who doesn't like "different," this may not be your thing. But if this write-up has left you curious, give it a shot. I switched to RPN as a senior in High School decades ago and never looked back.

I still have my original HP 15C from when I was in college decades ago, and it's still working. I installed this a few years ago as a backup just in case. I have used it quite a bit when l didn't have access to my original. The app works like a charm, just like the original. For those who have just downloaded the latest update and it has stopped working, go to the menu button and use the reset function. I had this happen to me just tonight but was able to reset it and it's working fine.

Like so many others, my hp15 and hp16 were my bread & butter calculators. I have always tried to understand the ins and outs of how to fully use them - especially with something as complex as the later hp calculators. I noticed the app works at the speed of the processor and not the programmer! (Don't you just HATE those sluggish, buggy apps!) It feels snappy and responsive. For the price of lunch for 2 at fast food, the app IS WORTH every penny. It truly replicates the genuine thing.

Looks and acts like the real thing... I love having it in my pocket wherever I am, rather than having to go get the real one from my desk when I need it. The simplified vertical layout is a nice plus for simple tasks.

I'm so happy!🤗 I have my beloved HP 15C on my phone! The one I bought in 1985 still works like new. This one on my phone just makes my day, even for $16.99, which is the most expensive app I've ever seen. I have complex technical engineering geology apps for $5.99. You'd probably sell a lot more if they were $5.99 or $2.99. Still love it! 😁

Brilliant use of portrait & landscape to switch between full HP15C and basic calculator mode. Update. Today (12/6) this app no longer responds to screetaps at all. Not sure when this happened, but PLEASE FIX IT. Reinstalled to no avail. Android9, Galaxy Note 8, Verizon. No response from HP when email sent to support. After Android security update 12/17, still broke, still no response from HP. Similar app on iPhone works OK.

Loved it. I have the real 15C and it is great to have it in app version in your phone. The original instruction manual is included so that was a bonus surprise. I hope they make a 16C version too.

Solution to -> the app stopped responding on my Galaxy S 7 after the last update. emailed developer link @ HP several weeks ago, no response! However, after uninstalling & reinstalling it started working again. So back to 5 stars ☆☆☆☆☆! Leaving the rating a one ☆ so others may find this fix. It would have been nice to get a response from HP...

Was a great app until it stopped working. Now the calculator display stays blank. Contacted support, but got no response at all. Update: the Reset fix suggested in another review worked for me as well.

I've had the calculator since they came out last century. when I found the 15c in the app store years ago, I was so happy to have the same calculator everywhere I went. I've been using it for I don't remember how long but it and it's compadre 12c are the best ever. Thank you HP for giving us both of these essential tools and migrating them to our smartdicktraceypocketwatch.

App stopped working when I got a new phone (Note 10). No numbers in the display area. Sent a message to HP and they ignored me. Here's an idea. If you want to charge $15 for an app, sell one that works. Don't ignore your users when your app stops working. You are a giant company. Fixing this would not burden your resources at all. Get your act together.

Obscenely priced, but the real deal. I've tried to avoid giving HP money for an emulator when they refuse to produce the calculator anymore, but every other available option falls short. If you want a 15C on your phone, this is the way to go.

I wish HP would re-release the 15c physical calculator in all its quality, robustness (drop proof) with a faster processor but alas, we have to settle on an app which HP may or may not maintain. Seeing as this app was last updated on 2017, I hold grave fears each time a subsequent version of Android is released. I certainly hope HP will continue to maintain this app but would celebrate a physical device release even more so! In short, the best scientific calculator on the planet.

For everyone having display issues, you just need to reset it. To reset, open the menu, where the power button normally is, and click on reset. It's really as simple as that. GLHF.

The app stopped working completely. I am unable to enter any numbers onto the register. This used to work superbly. Uninstalled and reinstalled but no change. Running this on a Galaxy S10.

I love using the RPN logic since buying the HP21 as my first calculator at university. Exchanged it later for the 15C - and the Android version is very handy today. However, since the software upgrade of my Samsung Note10 earlier this week (One UI for Android Pie), not all the buttons are active anymore.

I loved this app until I lost my ASUS Zenphone and bought a OnePlus 6T(which has a slightly smaller display?) Now the display is cut-off at the top and is unusable in landscape mode! No response when I sent in a bug report.

After reading reviews I was apprehensive, thoughit might not work. I have galaxy s9 with android 10, and I am having no issues. I had hp 11c back in the day, it was my favorite calculator of them all. This is every bit as good. It is pricey, but thanks for a great app.

Great app for the last 4 or so years. All of a sudden unresponsive. I would recommend when they fix the new problem.

Still have my 15C and still works. Love the app too. Basically, posting a solution to Darren Olson 2/7/20, I also experienced the "no numbers" problem, but all's normal after I performed a reset in the Menu.

I still have the original calculator and the app mimics it perfectly. In the last week or so, after years of using it, the app no longer takes any input. A bad update? I have uninstalled and reinstalled.

I was having some trouble with this app but I found a reset function under the menu button. The app is functional and very useful. Thanks HP I'm still a fan!

It was great until I got a new phone last week. Pixel 6. Screen opens ok but can't see numbers after pressing.

Great app with only one fault: If it had a full portrait mode it would be perfect.

It use to work great. However, after rhe last update the display is blank. Therefore, it is not usable.

Worked great until recently. Now the calculator does not function. There is nothing in the display after pressing any key. Samsung Galaxy S9

I love this app, it is the calculator that came out after the one I took to University. However, I'm really sad because I updated to a new phone and now the calculator no longer works. Is there a fix coming out?

Love this app! Works great on my Pixel 3. Still have my original 15c, but no longer carry it around...not that much of a nerd... anymore. Great to have it's functionality on my phone.