HP-42S Scientific Calculator

The HP-42S Scientific Calculator is a legendary Reverse Polish Notation (RPN) programmable calculator highly regarded by engineers, scientists, and professionals for its precision, reliability, and advanced computing capabilities. Designed for complex mathematical, engineering, and scientific applications, the HP-42S features a two-line LCD display, support for matrix operations, complex number calculations, and advanced statistical functions. Its programmable architecture allows users to create and store custom routines for repetitive or advanced calculations, making it ideal for professionals who require accurate and efficient results in the field or lab. Compact and rugged, the calculator maintains HP’s reputation for quality craftsmanship with a responsive keyboard and intuitive interface. Though discontinued, the HP-42S remains a highly sought-after model for those who value performance, portability, and the unmatched utility of classic RPN logic in professional problem-solving environments.

Product Features: 

• RPN Entry System – Efficient input method favored by engineers and technical users
• Advanced Scientific Functions – Includes matrix math, complex numbers, and statistics
• Programmable Memory – Store custom formulas and routines for repeated use
• Two-Line LCD Display – Clear viewing of inputs and results
• Compact & Durable Design – Built for reliable performance in demanding environments
• Battery Operated – Long-lasting use with standard coin cell batteries
• Legacy HP Build Quality – Trusted, professional-grade construction

Note: This is a refurbished item that comes with a 90-day exchange warranty. This has been serviced and calibrated to work as new. Servicing can include replacement of belts, gears, capacitors, cleaning and re-lubricating all internal mechanisms. Porter Electronics prides itself on only acquiring top quality used products that show minimal signs of use. Buying from Porter Electronics you should expect a very nice, refurbished unit. We do offer an extended warranty that can be purchased during checkout and will apply at the end of our already 90-day warranty

Porter Electronics also offers free tech support for those needing extra help. We offer a free digital download of the manual for this on this page in the “Downloads” tab. If you are unable to locate the link, just use our Contact Us page to request one.