kei-san

kei-san is a multifunctional calculator app that combines everyday calculations and study tools in one.
You can quickly switch between a scientific calculator, graph display, unit circle, trigonometric table, base conversion, and LaTeX preview.

Main Features

Scientific Calculator

Supports arithmetic, powers, square roots, trigonometric functions, inverse trigonometric functions, logarithms, calculus, statistical functions, etc.

Memory functions (MR / MC / M+ / M-)

Input assistance (cursor movement, DEL, BS, CLR)

Graph Display

Plot input expressions and compare multiple formulas

Legend display, toggle ON/OFF, scale settings, support for log-log graphs

Learning Support

Check the unit circle and trigonometric table simultaneously

Convert expressions to LaTeX and preview formulas

Base Conversion

Convert between binary, octal, decimal, and hexadecimal

Use Cases

Calculations and verification for school or qualification exams

Technical calculations and numerical checks at work

Verification and visualization of formulas in research and development

Features

Intuitive layout for easy use

Quickly switch between necessary functions on a single screen

Smooth operation on mobile devices

Notes

Calculation results may vary depending on input conditions and rounding.

Display may differ slightly depending on device or OS version.

Support

Terms of service, privacy policy, and contact information can be found in the in-app menu.