Mathematics
The Modular Arithmetic Clock and Its Use in Cryptography
Quick fact
The RSA encryption algorithm, which secures much of the internet, relies on modular exponentiation with enormous numbers—typically thousands of bits long—making reverse-engineering the private key computationally infeasible.
Why this is interesting
You use modular arithmetic every time you read a clock—but the same idea secretly protects your passwords, messages, and online transactions. How can a simple clock concept be the backbone of modern cryptography?