Numbers

About Numbers

The Numbers API, part of the math.tools suite, provides endpoints for retrieving numeric data and facts. It offers a "number of the day" endpoint, random number generation, and lookups covering number properties such as primality, parity, and palindrome status. Responses include representations of a given number in multiple bases (binary, ternary, quaternary, quinary, senary, octal, duodecimal, hexadecimal, vigesimal), numeral systems (Roman, Chinese, Egyptian, Babylonian), and word forms (cardinal, ordinal, nominal, US currency).

Requests are made to a dedicated API endpoint (api.math.tools) separate from the main math.tools site. Public calls require no API key and are rate-limited to 60 calls per day (5 per hour); paid subscriptions authenticate via an API key passed either as a request header (X-MathTools-Api-Secret) or a request parameter, with higher rate limits according to the subscription plan.

This API is suited for developers building applications that need programmatic access to number facts, base conversions, or numeral-system representations, such as educational tools, calculators, or utilities requiring formatted numeric output.

Key features

• Number of the day endpoint with cardinal, ordinal, and currency names
• Random number generation
• Base conversions (binary, ternary, quaternary, octal, hexadecimal, and more)
• Numeral system conversions (Roman, Chinese, Egyptian, Babylonian)
• Number property checks (prime, composite, odd, even, palindrome, perfect, Fibonacci)

Frequently asked questions