Mathematics
The Concept of Numbers (maths001)
Quick fact
The concept of zero as a number was a revolutionary leap—developed independently in India around the 5th century and in Mesoamerica centuries earlier—that made modern arithmetic and algebra possible.
Why this is interesting
You use numbers every day without thinking, but have you ever wondered what a number actually is—why '2' can represent two apples, two seconds, or two ideas, and how we can trust that 2+2 always equals 4?