Odd or Even Generator

The Odd or Even Generator produces random whole numbers and lets chance decide whether each one is odd or even. You choose how many digits each number should have and how many numbers you want, up to 64 at a time. Press the button and the list appears. Leave the digit length at 1 and you get single digits, which is the quickest way to settle an odds-and-evens call; set it to 3 or 4 when you need numbers for a classroom exercise or a game.

What the two settings do

• Number of digits controls the length of every number in the batch. With 1 you get 1 to 9; with 2 you get 11 to 99, and so on. The generator never uses the digit 0, so a 3-digit result will be between 111 and 999. Keep it at 15 digits or fewer: beyond that, JavaScript cannot represent the number exactly and the odd/even adjustment stops being reliable.
• How many to generate sets the batch size, from 1 to 64. If you clear the field, the tool picks a random count for you.

For each number the tool builds the digits, then flips a virtual coin. Heads means the number should be even, tails means odd; if the number does not match, 1 is added to fix the parity. Over a big batch you should see roughly half odd and half even, but any single number is a fair 50/50. You cannot force the whole batch to one side. If you need only odd numbers, generate a batch and keep the ones ending in 1, 3, 5, 7 or 9.

Ways to use it

• Odds and evens without hands. One person calls odd, the other even, generate a single digit, and the last digit decides. It replaces the finger-throwing game when you are on a call or in a chat.
• Splitting a group in two. Number people off, generate one number per person, and send odds to one side and evens to the other. For named teams the Random Team Generator does the split directly, and the Random Pair Generator makes pairs.
• Math practice. Generate twenty 3-digit numbers and have students sort them into odd and even, then explain the rule they used. Longer numbers make the "only the last digit matters" lesson stick.
• Roulette-style bets and board games. Any game that pays out on odd or even can use a batch as its draw list.
• A two-way decision. Assign one option to odd and the other to even, generate one number and go with it. For more than two options, the Random Picker or Spin the Arrow is a better fit.

Telling odd from even

A number is even when it divides by 2 with nothing left over and odd when it leaves a remainder of 1. In practice you only need the last digit: 0, 2, 4, 6 and 8 mean even; 1, 3, 5, 7 and 9 mean odd, no matter how long the number is. Zero counts as even. A few rules that come up in games and puzzles:

The classic hand game works on the addition rule: two players each show one to five fingers at the same time, and the sum decides. Since odd + odd and even + even are both even, "evens" wins slightly more often than you might expect against a player who throws at random (13 of the 25 combinations are even). The generator has no such bias, which is one reason to use it instead. Browse all fun, party & decision tools for other ways to let chance decide.