Retro 15C is a free iPhone app that brings back the nostalgia of classic RPN scientific calculators from the 1980s. Designed for students and scientists, this calculator strikes a perfect balance between functionality and complexity.

With Retro 15C, you can perform complex number arithmetic and trigonometric functions, making it ideal for advanced mathematical calculations. It also offers matrix calculations, numerical root finding, numerical integration, and statistical functions including linear regression. The app is fully programmable, allowing you to write and execute your own custom calculations.

One of the standout features of Retro 15C is its simplicity. The clean and intuitive interface makes it easy to navigate and use the calculator efficiently. The app is completely free, with no ads or additional purchases required.

If you have fond memories of using RPN calculators in the past or if you're a student or scientist in need of a reliable scientific calculator, Retro 15C is a must-have app for your iPhone. Experience the joy of using a classic calculator with modern convenience.