Let me give you a challenge. You don’t have to do much—just think of any number. If it’s even, divide it by 2. If it’s odd, apply the rule 3𝑛 + 1, where 𝑛 is the number you chose. Then take the result and repeat the same process again. If you keep doing these calculations, you’ll eventually notice that the sequence always ends at 1. And if you continue further, the numbers 4 → 2 → 1 will repeat over and over again. Now here’s the challenge: try this with as many numbers as you can think of. If you ever find a number that does not end in the 4 → 2 → 1 cycle, congratulations—you’ve just solved an 88-year-old mathematical mystery. Yes, mathematicians have tested trillions of numbers over the past 88 years, and so far, not a single number has been found that avoids ending in the 4 → 2 → 1 sequence. This is known as the 3𝑛 + 1 problem (Collatz conjecture).