Bring meaning to your metrics and stories to your dates with our API of interesting number facts.

Getting Started

Installing Dependencies

npm install

Run script to implement SASS styling from compass.

npm run scss

Start server on http://localhost:8124/

npm start

Running into issues

This API was built with Node version 10. If you experience issues while installing npm dependencies, try running install process with an older version of node. Versions 15 and 12 are able to run server.

See Node Version Manager for a great tool for switching between node versions.

URL Structure

Just hit http://numbersapi.com/number/type to get a plain text response, where

• type is one of trivia, math, date, or year. Defaults to trivia if omitted.
• number is
  • an integer, or
  • the keyword random, for which we will try to return a random available fact, or
  • a day of year in the form month/day (eg. 2/29, 1/09, 04/1), if type is date
  • ranges of numbers

http://numbersapi.com/42
⇒ 42 is the result given by Google and Bing for the query "the answer to life the universe and everything".

http://numbersapi.com/2/29/date
⇒ February 29 is the day in 1504 that Christopher Columbus uses his knowledge of a lunar eclipse to convince Native Americans to provide him with supplies.

http://numbersapi.com/random/year
⇒ 2013 is the year that China will attempt its first unmanned Moon landing.

Usage Examples

jQuery

HTML:

We now have more users than <span id="number"></span>!

JavaScript:

$.get('http://numbersapi.com/1337/trivia?notfound=floor&fragment', function(data) {
    $('#number').text(data);
});

Direct cross-origin requests like this are possible on browsers that support CORS. Live demo on JSFiddle.

Query Parameter Options

Fragment

Return the fact as a sentence fragment that can be easily included as part of a larger sentence. This means that the first word is lowercase and ending punctuation is omitted. For trivia and math, a noun phrase is returned that can be used in a sentence like "We now have more users than [fact as fragment]!".

http://numbersapi.com/23/trivia?fragment
⇒ the number of times Julius Caesar was stabbed

http://numbersapi.com/1969/year?fragment
⇒ an estimated 500 million people worldwide watch Neil Armstrong take his historic first steps on the Moon

Notfound

The notfound field tells us what to do if the number is not found. You can give us:

• default to return one of our pre-written missing messages, or a message you supply with the default query field. This is the default behaviour.

  http://numbersapi.com/314159265358979
  ⇒ 314159265358979 is a boring number.

• floor to round down to the largest number that does have an associated fact, and return that fact.

  http://numbersapi.com/35353?notfound=floor
  ⇒ 35000 is the number of genes in a human being.

• ceil, which is like floor but rounds up to the smallest number that has an associated fact.

  http://numbersapi.com/-12344/year?notfound=ceil
  ⇒ 98 BC is the year that the Senate passes the Lex Caecilia Didia which bans omnibus bills.

Combine with the fragment option to produce interesting facts about, for example, the number of page shares.

Default

The value of the default query field tells us what to return if we don't have a fact for the requested number.

http://numbersapi.com/1234567890987654321/year?default=Boring+number+is+boring.
⇒ Boring number is boring.

See the HTML embed tag usage example.

Min and Max

Restrict the range of values returned to the inclusive range [min, max] when random is given as the number.

http://numbersapi.com/random?min=10&max=20
13 is the number of provinces and territories in Canada.

JSON

Include the query parameter json, or set the HTTP header Content-Type to application/json, or set the HTTP header Accept to application/json to return the fact and associated meta-data as a JSON object, with the properties:

• text: A string of the fact text itself.
• found: Boolean of whether there was a fact for the requested number.
• number: The floating-point number that the fact pertains to. This may be useful for, eg. a /random request or notfound=floor. For a date fact, this is the 1-indexed day of a leap year (eg. 61 would be March 1st).
• type: String of the category of the returned fact.
• date (sometimes): A day of year associated with some year facts, as a string.
• year (sometimes): A year associated with some date facts, as a string.

http://numbersapi.com/random/year?json
⇒ {
    "text": "2012 is the year that the century's second and last solar transit of Venus occurs on June 6.",
    "found": true,
    "number": 2012,
    "type": "year",
    "date": "June 6"
}

Batch Requests

To get facts about multiple numbers in one request, specify ranges for number in http://numbersapi.com/number/type.

A number range (inclusive) is specified as min..max. Separate multiple ranges and individual numbers with , (a comma).

The response format will always be a JSON map from numbers to facts, of at most 100 numbers. The query parameter json may still be used to specify whether individual facts will be returned as string literals or JSON objects.

http://numbersapi.com/1..3,10
⇒ {
    "1": "1 is the number of dimensions of a line.",
    "2": "2 is the number of polynucleotide strands in a DNA double helix.",
    "3": "3 is the number of sets needed to be won to win the whole match in volleyball.",
    "10": "10 is the highest score possible in Olympics gymnastics competitions."
}

Deprecated Features

Callback

To use JSONP, pass to the callback query the name of the JavaScript function to be invoked. The response will be that function called on the fact text as a string literal.

http://numbersapi.com/42/math?callback=showNumber
⇒ showNumber("42 is the 5th Catalan number.");

See the JSONP usage example.

JSONP

...is supported with the query field callback:

<span id="number-fact"></span>

<script>
    function showNumber(str) {
        document.getElementById('number-fact').innerText = str;
    }

    (function() {
        var scriptTag = document.createElement('script');
        scriptTag.async = true;
        scriptTag.src = "http://numbersapi.com/42/math?callback=showNumber";
        document.body.appendChild(scriptTag);
    })();
</script>

Live demo on JSFiddle.

Write

We do not recommend using document.write() because of possible cross-site scripting attacks.

Returns the text response wrapped in a call to document.write(). Note that using this query parameter is equivalent to and just a shorthand of ?callback=document.write.

http://numbersapi.com/42/math?write
⇒ document.write("42 is the 5th Catalan number.");

HTML Embed

Add write to your query string to have the response text wrapped in document.write(). Now you can stick just a single <script> directly where the fact should go.

Did you know 2012 is the year that <script src="http://numbersapi.com/2012/year?write&fragment"></script>?

Note that this may degrade page load speed. Live demo on JSFiddle.

Contributing

Numbers API is an evolving project. If you would like to contribute to the code base, suggest any ideas, or even just submit a number fact, please visit our Github.