Master Counting Principles: Easy Examples and Guides

brooklyn stokes

12/6/2025

Statistics

Counting Principles and Examples

Subjects

Statistics

Overview

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Dec 6, 2025

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2 pages

Master Counting Principles: Easy Examples and Guides

brooklyn stokes

@brooklynstokes_gllcu

Counting principles help us figure out how many different ways... Show more

Name:
Topic:
Brooklyn Stokes
Main Ideas/Questions
FUNDAMENTAL
COUNTING PRINCIPLE
EXAMPLES
S
CA
4-2=26
0-9 = 10 (digits)
FACTORIALS
M.!
mathP

Fundamental Counting & Permutations

Ever wondered how many possible license plates exist? The Fundamental Counting Principle gives us the answer! When you have multiple decisions to make, multiply the number of ways to make each decision.

For example, if an ice cream shop offers 3 cone sizes, 15 flavors, and 8 toppings, you can create 3 × 15 × 8 = 360 different cones. Similarly, Virginia license plates with three letters followed by four digits have 26³ × 10⁴ = 17,576,000 possibilities!

Factorials are another important counting tool, representing the product of all natural numbers from n down to 1. For example, 5! = 5 × 4 × 3 × 2 × 1 = 120. Remember that 0! equals 1, which is a special case.

Permutations help us count arrangements where order matters. The formula is ⁿPᵣ = n!/ $n-r$ !, where n is the total objects available and r is how many you're using. When arranging all objects $n=r$ , you can simply use n!. For instance, arranging 7 students in first, second, and third place gives ⁷P₃ = 7!/(7-3)! = 210 possibilities.

Quick Tip: Think about whether order matters in your problem. For arranging students in a line or determining finishing positions in a race, order definitely matters—that's a permutation!

More Permutations & Combinations

When letters repeat in a word, the permutation formula needs adjustment. For example, to find arrangements of "AUTOMOBILE" (with two 'O's), divide by the factorial of the repetition: 10!/2! = 1,814,400 possible arrangements.

Combinations come into play when order doesn't matter - like selecting team members where you only care who's on the team, not their positions. The formula is ⁿCᵣ = n!/ $r!(n-r)!$ . If you're choosing all available objects $n=r$ , there's only 1 way to do it.

Real-life applications of combinations include choosing bridesmaids from friends $16 friends, choosing 5 = 4,368 possibilities$ or selecting students for a party $24 students, choosing 8 = 735,471 ways$ . The formula helps determine how many different groups are possible.

When faced with a counting problem, always ask yourself: Does order matter? If yes, use permutations. If not, use combinations. For example, selecting kittens to adopt from a pet store uses combinations since you just care which kittens you get, not the order you choose them.

Remember This: Permutations are for arrangements (like batting orders or schedules) while combinations are for selections (like committee members or party guests). The P or C in the formula tells you which you're dealing with!

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Subjects

Statistics

Overview

Statistics

•

Dec 6, 2025

•

2 pages

Master Counting Principles: Easy Examples and Guides

brooklyn stokes

@brooklynstokes_gllcu

Counting principles help us figure out how many different ways things can happen or be arranged. This guide breaks down fundamental counting, permutations, and combinations - essential math concepts that help solve real-world problems involving choices and arrangements.

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Fundamental Counting & Permutations

Quick Tip: Think about whether order matters in your problem. For arranging students in a line or determining finishing positions in a race, order definitely matters—that's a permutation!

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Access to all documents

Improve your grades

Join milions of students

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More Permutations & Combinations

Remember This: Permutations are for arrangements (like batting orders or schedules) while combinations are for selections (like committee members or party guests). The P or C in the formula tells you which you're dealing with!