The HP 35s uses either Reverse Polish Notation (RPN) or algebraic infix notation as input. Other features of the HP 35s include: Two-line alphanumeric LCD Over 800 memory registers (26 directly labelled. Scientific and statistical functions Operation in decimal, binary, octal, hexadecimal Support for input and display of fractions Complex number and vector calculations Unit conversions and table of physical constants Keystroke programmability with approximately 30 kilobytes of memory for programs and data The calculator will be packed carefully.