calculator_skill

Overview

This skill performs arbitrary-precision arithmetic using a decimal math library to avoid floating-point errors. It handles addition, subtraction, multiplication, division, integer exponents, and parenthetical expressions with correct operator precedence. Use it when exact decimal results matter or when evaluating user-supplied arithmetic expressions.

How this skill works

The skill parses a textual arithmetic expression, respecting parentheses and operator precedence, then evaluates it using arbitrary-precision decimal arithmetic (big.js). Exponentiation is right-associative and requires integer exponents. Errors are raised for empty input, mismatched parentheses, division by zero, or non-integer exponents.

When to use it

• When a user asks to calculate, compute, or evaluate a math expression
• When precise decimal results are needed (avoid 0.1 + 0.2 floating-point noise)
• When expressions include parentheses and operator precedence
• When working with integer exponents and high-precision decimal arithmetic
• For simple numeric evaluation without variables or symbolic math

Best practices

• Provide a single well-formed expression string without variables
• Use parentheses to make precedence explicit and avoid ambiguity
• Keep exponents as integers to ensure correct evaluation
• Validate input length and characters before evaluation to prevent injection
• Handle and surface errors: empty input, mismatched parentheses, division by zero

Example use cases

• Evaluate money calculations where exact decimal cents matter (e.g., 19.95 * 3 / 7)
• Compute nested expressions with parentheses like (2 + 3) * 4 or 1 + 4.5 * (3 - 6) / 5
• Calculate large integer powers such as 2 ^ 10 or right-associative chains like 2 ^ 3 ^ 2
• Avoid JavaScript floating-point surprises such as 0.1 + 0.2
• Run quick arithmetic checks inside scripts or tools that require precise decimal output