Understanding Factorials: Why 7! = 5040, 3! = 6, and 2! = 2

Factorials are a fundamental concept in mathematics, especially in combinatorics, permutations, and probability. Whether you’re studying for exams or simply curious about how numbers multiply to create larger results, understanding factorials is essential. In this article, we’ll explore three key factorial values—7! = 5040, 3! = 6, and 2! = 2—and explain why these equations hold true.

What Is a Factorial?

Understanding the Context

A factorial of a non-negative integer \( n \), denoted by \( n! \), is the product of all positive integers from 1 to \( n \). Formally:

\[
n! = n \ imes (n-1) \ imes (n-2) \ imes \cdots \ imes 2 \ imes 1
\]

For \( n = 0 \), by definition, \( 0! = 1 \), which serves as a foundational base case.

7! = 5040 — The Power of Multiplication

Key Insights

Let’s begin with the equation:

\[
7! = 7 \ imes 6 \ imes 5 \ imes 4 \ imes 3 \ imes 2 \ imes 1
\]

Calculating step by step:

\[
7! = 7 \ imes 6 = 42 \
42 \ imes 5 = 210 \
210 \ imes 4 = 840 \
840 \ imes 3 = 2520 \
2520 \ imes 2 = 5040 \
5040 \ imes 1 = 5040
\]

Thus, \( 7! = 5040 \). Factorials grow very quickly, which explains why large values like 7! result in significant numbers—even though the numbers themselves are sums of smaller products.

Final Thoughts

3! = 6 — A Simple Factorial Example

Moving to a smaller factorial:

\[
3! = 3 \ imes 2 \ imes 1 = 6
\]

This shows how factorials simplify multiplication of sequences. For \( n = 3 \), the calculation involves multiplying three descending integers, yielding 6. This basic example helps illustrate how factorials build on multiplication principles.

2! = 2 — The Minimal Factorial

The factorial of 2 is likewise straightforward:

\[
2! = 2 \ imes 1 = 2
\]

Even the smallest factorial equals the number itself—attesting to the identity-like nature of \( 1! = 1 \) and \( 2! = 2 \). This simplicity reveals how factorial operations scale from the smallest case upward.

Why Factorials Matter

Beyond these three examples, factorials are vital in mathematics and real-world applications: