Pi.Mathematika | Math Learning on Instagram: "why the Factorial of O is 1 (0!=1) ? The factorial of zero, written as 0!, equals 1 because of how patterns in mathematics work. When you multiply numbers in decreasing order (like 5! = 5×4×3×2×1), each step follows a consistent rule. To keep that pattern valid, mathematicians define 0! = 1. It also fits perfectly in combinatorics—there’s exactly one way to arrange zero objects: doing nothing! This definition ensures formulas in algebra, calculus, an