Modular arithmetic is another intriguing concept in number theory that deals with remainders. It involves performing calculations based on a fixed modulus. For example, in a clock that follows a 12-hour format, after 7 hours, we end up at 7 o'clock. If we add 5 more hours, which is equivalent to 12 modulo 7, we end up at 12 o'clock (noon). Modular arithmetic finds applications in cryptography, computer science, and even music theory. It helps us understand repeating patterns and cyclic behavior.