1/31/2026 at 10:16:58 AM
I have an old HP 15C RPN scientific calculator.- I know where the buttons are without looking.
- It has functions my Android calculator does not have (directly or that I know of).
- It has a strange satisfying tactile feedback.
- It never interrupts me. Ever.
- It never distracts me. Ever.
I reach for it frequently.
by readingnews
2/3/2026 at 1:40:49 PM
IMHO the HP 15C RPN is the best calculator ever made. I still have the original with the slip case and manual. However, more often these days i just use my phone's calculator without RPN (i don't need to do a lot of complicated math for mechanical engineering -- we use tables for most stuff). I reached a point/decision several years ago to protect my HP 15C for posterity.by commakozzi
1/31/2026 at 4:04:39 PM
I can't think of another electronic device that has survived and remained useful for half the 43 years my 15C has - through two years of high school, a math degree, and an entire software engineering career. When I calculate something any other way, it involves thinking about what my thumbs automatically do on my 15C and translating that.When I'm away from it, there's a wonderful emulation of the 15C (and 16C) at https://jrpn.jovial.com. The numeric algorithms behave identically as far as I can tell, and it even includes the back panel (3-dot menu near the logo, then "Help"). The visuals make me feel right at home. If only they could reproduce the tactile experience.
by rented_mule
1/31/2026 at 10:50:22 AM
I've never owner any other piece of technology with buttons this good.It is really a lost art.
by silvestrov
2/3/2026 at 6:13:03 PM
I smilarly use the HP 12c. There is nothing more convenient for solving simple compound interest/discounting problems.by kqr