How to use this manual

SpicyRPN combines scientific and financial calculation with multiple-precision arithmetic. It offers two ways to work: reverse Polish notation (RPN), in which you enter operands before an operation, and algebraic entry (ALG), in which you write an expression. Choose the approach that suits the calculation and your experience.

You do not need to read this book from beginning to end. Start with the calculator’s layout and the entry mode you intend to use, then turn to the functions you need. The main text explains everyday operation; the appendices provide extended RPN instruction, mathematical detail, and source-build information.

Choose your starting point

If you already use RPN, begin with the display and keyboard tour in chapter 1, then read chapter 2. Familiarity with another calculator is useful, but stack depth, entry, clearing, and operand recovery deserve particular attention in SpicyRPN. Afterward, go directly to the scientific, statistical, or financial functions you need.

If you are learning RPN, follow the orientation with chapter 2 and chapter 3, in that order. The stack explains where your numbers go and which numbers an operation uses. Try the short calculations before moving to the more detailed instruction and practice in chapter A. For the reasoning and history behind this style of calculation, see chapter B.

If you prefer algebraic entry, read the orientation and chapter 4, then use the shared chapters on precision, scientific functions, complex numbers, and conversions. The memory, statistics, and financial chapters include ALG worksheet procedures as well as RPN examples. Follow the procedure for your entry mode: worksheet fields replace stack operand positions in ALG.

Keys, registers, and display notation

The manual distinguishes a key you press from a number or indicator you read. On a touch screen, “press” means tap the corresponding key. When a physical-keyboard shortcut is intended, the instructions identify it explicitly.

X and S0 name the same position; so do Y and S1. The manual uses X and Y to match function names and operand formulas. LAST X and LAST Y recall saved operands from earlier operations; those saved values are separate from the values currently in S0 and S1. ALG worksheet fields and mathematical variables named X or Y are identified in their own context; they do not refer to the inactive RPN stack.

Read a key sequence from left to right. Consecutive key symbols mean successive presses, not keys held down together. When a sequence shows f or g, press that shift key first, then the key carrying the named orange or blue function. The function name, as well as the color, identifies the intended operation.

Numbers written as ordinary input, such as 125.75, mean enter those digits and the decimal point in order. A mathematical expression such as \(3(4+5)\) describes a calculation; it is not a key sequence unless explicitly presented as one. In an RPN stack diagram, the register labels identify each value’s position. Read those labels before tracing how an operation moves or combines values.

Following the examples

Check an example’s starting conditions before entering its numbers. Entry mode, angle unit, precision, and display format can affect what you see. Financial examples also depend on cash-flow signs, the interest period, payment timing, and values already stored in the financial registers. Clearing the display alone does not clear every memory bank.

Follow an example’s key sequence in order and compare the stated result with your display. A table of intermediate results lets you locate the first point at which your calculation differs. Where an example gives a rounded result, use the stated display format when comparing its final digits. A different display format can show the same underlying value in a different way.

For the distinction between working digits, displayed digits, and input accuracy, see chapter 5.

Finding a function or solving a problem

For an explanation and worked use, turn to the relevant subject chapter. For a key sequence, operands, mode availability, or side effects, use the command reference in chapter 15. The table of contents provides the book’s structure; the index provides access by function and subject. In the PDF, the contents, cross-references, and bookmarks help you move between related topics.

Chapter 14 explains saved work, clearing operations, errors, and common causes of unexpected results. Chapter C gives the formulas and numerical conventions behind the calculations. Readers who want to build or modify SpicyRPN can turn to chapter D.

Application and manual versions

This manual is dated 18 October 2026 and identifies the application as version 2.0.0 (build 3). Match the application version and build when comparing behavior or reporting a problem. Include the entry mode, relevant settings, starting values, and key sequence so the calculation can be reproduced.

Both modes provide scientific, statistical, financial, conversion, and memory functions. RPN uses stack operands; ALG uses expressions, explicit computation, and labeled worksheets. The command reference identifies each mode’s controls, and the individual chapters explain the required entry sequence.