Free42, developed by Thomas Okken, is a free, open-source re-implementation of the HP-42S scientific programmable calculator. Available across a variety of platforms, it reproduces most of the functionality of the original device and supports operations ranging from basic arithmetic to advanced scientific functions, consistent with the capabilities of the HP-42S.

Designed for diverse calculations

Free42 supports a wide range of mathematical tasks, from basic operations to advanced scientific functions. It includes capabilities for complex numbers and matrix operations, as well as built-in trigonometric, logarithmic, and statistical functions. Free42 also maintains compatibility with the HP-42S programming model, allowing users to create and run calculator programs as on the original device.

Accuracy and functionality

Free42 provides high numerical accuracy and reproduces most of the functionality of the original HP-42S calculator. It supports both Binary and Decimal floating-point modes on desktop platforms, while the mobile versions use the Decimal engine only.

A modern way to use a classic calculator

Free42 brings the classic HP-42S calculator into today’s world in a simple and reliable way. It keeps the original functions people loved, from basic math to advanced science features, while adding the benefits of modern software. Open-source and easy to access, Free42 is a handy tool for anyone who wants a trustworthy scientific calculator with a proven design.