The Collatz conjecture

The Collatz conjecture is an unsolved mathematical question about a simple process applied to any positive whole number: if the number is even, divide it by two; if odd, multiply it by three and add one. Repeating these steps, the process seems to always reach the number 1, regardless of the starting number. After reaching 1, the cycle repeats indefinitely. Although tested on many numbers and believed true, no one has proven that all starting numbers eventually reach 1, making it a famous puzzle in mathematics.