RPN-55 SD
RPN-55 SD is #94 in Productivity Paid in United States and charting in 1 of 24 countries we track.
Updated 28 Sep 2026 · rankings refresh through the day
DeveloperCuVee Software
CategoryProductivity
Price1.99 USD
Released
Rating★ 5.0 (8)
Version3.3
Age rating4+
First seen by us
28 Sep 2026
Rating
5.0 ★
8 ratings
Measured
Best rank now
#94
Measured
RPN-55 SD on the App Store
App details
App ID
1469907917
Publisher
Willy Kunz
On the store since
Jul 2019
7 years on the store
Minimum OS
iOS 12.0+
iPhone 5s and later
Devices
iPhone · iPad
Content rating
4+
Languages
1
EN
Size
18 MB
Also listed in
Utilities
Where it ranks now
Every top chart it appears in across 24 countries.
| Country | Charts | Rank |
|---|---|---|
| ProductivityPaid | #94 |
Apps near RPN-55 SD on the chart
Productivity Paid, around #94.
Ratings
App Store, worldwide.
Rating
5.0 ★
8 ratings
Measured
Ratings
8
Measured
About RPN-55 SD
RPN-55 SD is the first photo-realistic simulation for the iPhone of Hewlett-Packard's low-cost alternative to the famous HP-65 programmable scientific calculator. Produced from 1975 through 1977, it was the "Merlin" member of the classic HP calculator series, priced at $395. HP claimed that it featured "(...) more pre-programmed functions than any other scientific pocket calculator in the world."
A main feature of the HP-55 was a crystal-controlled 100-hr digital timer with the ability to store times while the timer was running and later recall them. On RPN-55 SD the timer may also act as a 12-hr or 24-hr clock, including date and weekday display.
While the simulator works just like the original calculator – except being much faster and having twice the program memory – you can turn on extended features to make it even more enjoyable to use.
RPN-55 SD comes complete with original HP programs built in.
Features:
• Photo-realistic look-and-feel
• Vintage mode or Extended mode
• Programmable (99 steps), conditional branching
• Insert and delete steps with automatic address correction
• Delete range of steps
• Subroutines (4 levels)
• 20 registers, "continuous", with unrestricted store/recall arithmetic
• "Live" register view
• Program listing view
• Program library view
• Store and retrieve any number of programs
• 100-hr timer supporting 10 split times and 12/24-hr clock mode with date
• Swap unit conversions with additional functions, e.g. hyperbolics
• Sharing: e-mail, AirDrop, Dropbox, copy, paste, print
• 112 programs pre-installed
Calculator functions:
• Statistics (linear regression, mean, standard deviation, correlation coefficient, x- and y-estimates)
• Trigonometric functions (degrees, radians, grads)
• Polar/rectangular conversions
• Inverse, square root, logarithm, exponential, pi
• Storage arithmetic (store and recall)
• Percent, absolute, integer, fractional value, round
• Factorial
• Random number
• Unit and hours conversions
Details: cuveesoft.ch/rpn55
A main feature of the HP-55 was a crystal-controlled 100-hr digital timer with the ability to store times while the timer was running and later recall them. On RPN-55 SD the timer may also act as a 12-hr or 24-hr clock, including date and weekday display.
While the simulator works just like the original calculator – except being much faster and having twice the program memory – you can turn on extended features to make it even more enjoyable to use.
RPN-55 SD comes complete with original HP programs built in.
Features:
• Photo-realistic look-and-feel
• Vintage mode or Extended mode
• Programmable (99 steps), conditional branching
• Insert and delete steps with automatic address correction
• Delete range of steps
• Subroutines (4 levels)
• 20 registers, "continuous", with unrestricted store/recall arithmetic
• "Live" register view
• Program listing view
• Program library view
• Store and retrieve any number of programs
• 100-hr timer supporting 10 split times and 12/24-hr clock mode with date
• Swap unit conversions with additional functions, e.g. hyperbolics
• Sharing: e-mail, AirDrop, Dropbox, copy, paste, print
• 112 programs pre-installed
Calculator functions:
• Statistics (linear regression, mean, standard deviation, correlation coefficient, x- and y-estimates)
• Trigonometric functions (degrees, radians, grads)
• Polar/rectangular conversions
• Inverse, square root, logarithm, exponential, pi
• Storage arithmetic (store and recall)
• Percent, absolute, integer, fractional value, round
• Factorial
• Random number
• Unit and hours conversions
Details: cuveesoft.ch/rpn55
Latest updates
3.3
• Improved compatibility with iPhone Air and iOS 26.