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In a room of just 23 people, it's more likely than not that two share a birthday.

In a room of just 23 people, it's more likely than not that two share a birthday.

It feels surprising, but you're comparing every possible pair of people, not just yourself against the others. With 23 people there are 253 possible pairs, which tips it over 50%. This is called the 'birthday paradox'.

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More facts about Numbers

The Romans had no symbol for zero. The Romans had no symbol for zero. A 'googol' is a 1 followed by one hundred zeros. A 'googol' is a 1 followed by one hundred zeros. A “googol” is the number 1 followed by 100 zeros. A “googol” is the number 1 followed by 100 zeros. Numbers help us tell how many things there are. Numbers help us tell how many things there are. Zero is the only number that can't be written with Roman numerals. Zero is the only number that can't be written with Roman numerals.