GO-21 SciRPN simulates the venerable HP-21 Pocket Scientific Calculator from 1975. Virtually indistinguishable from the real item in operation, GO-21 is a powerful yet simple retro calculator.

GO-21 combines the classic behavior of the HP-21 with modern iPhone capabilities like key click sounds, visual touch feedback, persistent stack, memory and display format, and help information.

• Requires iOS 4.3 or later
• RPN
• Copy / Paste
• Shake to clear X
• Swipe gestures that roll and display the stack
• Addition, subtraction, multiplication, division
• Trigonometric functions : sin, cos, tan, sin⁻¹, cos⁻¹, tan⁻¹, degrees or radians
• Rectangular/polar coordinate conversion
• Logarithmic functions : log, 10**x, ln, e**x
• Other functions : Y**x,1/x, √x, π
• Display : LED, 10 significant digits (8 + 2 digit exponent in scientific notation), 10-99 to 10+99
• Memory : 4 register stack, stack roll down, X-Y interchange, manual memory with register math
• floating stack and memory window