Plus42 4+

Thomas Okken

    • $9.99

iPhone Screenshots


Plus42 is an advanced scientific programmable calculator, based on Free42. Free42, in turn, is a complete re-implementation of the HP-42S scientific programmable RPN calculator, which was made from 1988 until 1995 by Hewlett-Packard. Free42 is a complete rewrite and contains no HP code whatsoever.

Plus42 builds on Free42 and adds: Algebraic expressions modeled after those used on the HP-27S and HP-17B/19B; attached units and unit conversions modeled after those used on the HP-48/49/50 series; directories for more organized storage of programs and variables; a larger display, with 8 rows and 22 columns (131x64 pixels) by default, which the user may resize at will; time value of money and amortization schedules; and two-dimensional plotting of functions, with ability to zoom and pan, and find integrals and roots from points in the plot.

What’s New

Version 1.0.16

EDIT, EDITN, and INDEX now support lists, acting like they are 1-column matrices. (Empty lists are not supported, they must have at least one element. This limitation will be removed in a future release. Note that you can create a new 1-element list by simply doing NEWLIST 0 +.)
This includes STOIJ, RCLIJ, STOEL, RCLEL, I+, I-, J+, J-, ←, ↑, ↓, →, INSR, DELR, and DIM.

Equation editor: now inserts spaces around logical AND, OR, XOR, and NOT.

Added PRREG. Because PRV "REGS" is not a good substitute.

Added NN→S. This works like N→S (convert number to string on the stack), but without the 12-digit mantissa length limit, so you get full precision in ALL mode.

Fixed stack lift handling in DELR and STOFLAG.

Fixed pasting 1/X, 10^X, and 4STK, when pasted without line number and with trailing space.

PRP and LIST in TRACE mode now print line numbers for all lines that are targets of GTOL or XEQL, like it already did for LBL lines.

Fixed pasting of GTOL and XEQL.

Ratings and Reviews

5.0 out of 5
35 Ratings

35 Ratings

akhan.a ,

Amazing reinvented.

I own multiple copies of the HP 42S, the DM42, but unlike those machines, my iPhone is always in my pocket. I have completely uninstalled the default calculator app and use the Free42 application quite heavily. I was really glad to see an upgrade with a bigger screen, so that I have something that’s close to the DM42 in my pocket at all times. This, I tell my students, is the best calculator ever made by man or beast. Thanks, Thomas!

DarkRadon ,

Lives in my Home Screen

This app goes above and beyond expectations. Very impressive work done to make this calculator what it is. Yes, it’s a bit nostalgic in terms of the looks, but this calculator is super useful! Lots of great loving care went into making this the best modern “HP RPN” calculator on the planet that’s not made by HP, but made by a developer who clearly puts forth passion in his work.

Bprijadi ,

The best calculator-computer period

With some programming, this can replace both of my units conversion and finance calculators apps. It is that powerful. I hope - and still have not figured out - we could use and call the TVM variables (PMT, FV, etc) in our custom programs, rather than duplicate the already available functions.

Developer Response ,

Yes, you can use the TVM functions in programs. Use STO "N", STO "I%YR", etc., to set the known parameters, and then use the N, I%YR, etc. functions to calculate the unknowns. Note that all of N, I%YR, PV, PMT, FV, BEGIN, and P/YR must be set, or you'll get a Nonexistent error. (The value being calculated does not have to be set in advance; its value is ignored.)

App Privacy

The developer, Thomas Okken, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Collected

The developer does not collect any data from this app.

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    Up to six family members can use this app with Family Sharing enabled.

More By This Developer

You Might Also Like