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OddMaths
Est. whenever numbers got weird

OddMaths — Maths is stranger than you think.

Numbers get weird. Let's make sense of it. Why don't two 50% changes cancel out? Why is 2 the only even prime? And why does a room of just 23 people already give you better than even odds of a shared birthday? Follow the weirdness, find the explanation, and test what you remember.

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From the Vault

Today's Weird NumberWeird Numbers

2: The Lonely Even Prime

Every even number is divisible by 2. Only one of them gets away with it.

Meet it

Numbers have personalities

1

weird numbers uncovered so far. New ones land all the time.

Today's Wrong FeelingMaths That Feels Wrong

50% Up, 50% Down

A 50% rise and a 50% drop don't cancel out. Ever.

See why

Trust the maths, not the vibe

1

counterintuitive results explained so far. New ones land all the time.

Today's ProbabilityChance & Probability

The Birthday Problem

23 people in a room. Already better-than-even odds two share a birthday.

Work it out

Chance is sneakier than it looks

1

probability surprises explained so far. New ones land all the time.

Pick a rabbit hole

Explore OddMaths

Wonderfully strange corners of mathematics. Start anywhere — every path leads somewhere surprising.

Feeling curious?

Let maths surprise you.

One tap, one random discovery: a counterintuitive number, a puzzle with a twist, a probability result that doesn't feel true, or a bit of everyday maths you'll start noticing everywhere.

?

Press the button.

Maths will do the rest.