## Factorials? What are They? A Simple Kind of Mathematics Shorthand

What are factorials? A variable is a symbol, often written as a letter of the alphabet that stands for a number that can vary in value. For example, take your age. That varies every year, doesn’t it? This year your age may be, say 21. If so, in 365 days your age will be 22. Another 365 days after that and your age will be 23. Thus age is a function of time. For you, we can write right now: A = 21 If the number of years that pass equals n, then for next year, n = 1 and An = 21 + n So, A₀ = 21 + 0 = 21 A₁ = 21 + 1 = 22 A₂ = 21 + 2 = 23 A₃ = 21…