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Uniformly selected from 50 even numbers between 2 and 100.
An even number is any integer divisible by 2 with zero remainder. The Pythagoreans classified whole numbers into even and odd around 500 BCE, making this one of the oldest formal distinctions in mathematics. Euclid formalized the definition in Book VII of the Elements: "An even number is that which is divisible into two equal parts." Exactly half of all integers are even. This density holds across every range: between 1 and 100, there are 50 even numbers; between 1 and 1,000,000, there are 500,000.
Every even number ends in 0, 2, 4, 6, or 8. This holds in base-10 because 10 is itself even: any number whose final digit is divisible by 2 is divisible by 2. The distribution bar in the statistics panel above tracks which of these five digits appears at the end of each generated number. For large uniform ranges, the five digits converge toward equal frequency (20% each), because even numbers ending in each digit are equally spaced throughout any sufficiently large range.
Smaller ranges reveal interesting asymmetries. Between 1 and 10, the even numbers are 2, 4, 6, 8, 10: last digits 2, 4, 6, 8, 0, each appearing exactly once. Between 1 and 18, the distribution shifts: last digits 2, 4, 6 each appear twice while 0 and 8 appear once. The convergence toward uniformity makes an engaging visual demonstration. Generate enough numbers and the five bars equalize.
In 1742, Christian Goldbach wrote a letter to Leonhard Euler proposing that every even integer greater than 2 can be expressed as the sum of two prime numbers. This statement, known as Goldbach's conjecture, remains one of the oldest unsolved problems in all of mathematics. Every even number generated on this page almost certainly satisfies it: modern computers have verified the conjecture for every even number up to 4×1018 without finding a single counterexample. The conjecture connects even numbers to the distribution of primes, two of the most fundamental structures in number theory.
This generator selects uniformly from all even numbers in the specified range. A single call to crypto.getRandomValues() produces a 32-bit random integer from your browser's Web Cryptography API, the same hardware-seeded entropy source that secures online banking. Rejection sampling eliminates modulo bias, ensuring that every even number in the range has exactly equal probability. The result never touches any server.
Even numbers introduce students to divisibility, the most foundational concept in number theory. Have each student generate 20 even numbers using /even/1/100 and record the last digit of each result. Pool the class data and count how many of each last digit appeared. The aggregate should approach 20% per digit. Ask students to predict the result before pooling: most will guess that the distribution should be perfectly even, yet individual samples will show visible variation. This contrast between individual randomness and collective predictability mirrors the central lesson of statistical sampling.
For a deeper exercise, compare even number generation across different ranges: /even/1/10 (only 5 possible values), /even/1/1000 (500 possible values), and /even/-100/100 (101 possible values including zero and negatives). The tool requires no accounts and collects no student data.
The URL defines the range completely:
Every number generated on this page originates from your browser's Web Cryptography API. The server delivers the interface. Your device produces every outcome. History lives in localStorage under your control alone. No accounts, no cookies, no result data stored on any server.
Pick a preset or type your own. The URL updates and the tool reloads.
Send this link. They generate their own even number from the same range.
Daily Inspiration
Jury-selected work from the A' Design Award, presented fresh each morning.
