Common Factor Calculator

Find all common factors and the greatest common factor (GCF) of two numbers

Enter Two Numbers

Enter any positive or negative integer

Enter any positive or negative integer

Factor Analysis Results

18
Greatest Common Factor (GCF)

Common Factors

1236918

Total: 6 common factors

Factors of 54

12369182754

Total: 8 factors

Factors of 72

12346891218243672

Total: 12 factors

Step-by-Step Solution

Step 1: Find all factors of 54
Factors of 54: 1, 2, 3, 6, 9, 18, 27, 54
Step 2: Find all factors of 72
Factors of 72: 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72
Step 3: Identify common factors
Common factors: 1, 2, 3, 6, 9, 18
Step 4: Greatest Common Factor (GCF) = 18

Example Calculations

Example 1: Numbers 54 and 72

Factors of 54: 1, 2, 3, 6, 9, 18, 27, 54

Factors of 72: 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72

Common factors: 1, 2, 3, 6, 9, 18

Greatest Common Factor (GCF): 18

Example 2: Numbers 12 and 24

Factors of 12: 1, 2, 3, 4, 6, 12

Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24

Common factors: 1, 2, 3, 4, 6, 12

Greatest Common Factor (GCF): 12

Factor Properties

1

Factor Definition

A number that divides evenly into another

Remainder is always zero

CF

Common Factors

Factors shared by both numbers

Always includes 1

GCF

Greatest Common Factor

Largest common factor

Also called GCD

Key Concepts

Every integer has at least two factors: 1 and itself

Common factors are always divisors of both numbers

GCF is useful for simplifying fractions

For prime numbers, GCF with other numbers is usually 1

Factor pairs multiply to give the original number

Understanding Common Factors

What are Factors?

A factor of a number is any integer that divides evenly into that number with no remainder. For example, the factors of 12 are 1, 2, 3, 4, 6, and 12 because each of these numbers divides into 12 exactly.

Common Factors

Common factors are numbers that are factors of two or more numbers. They represent the divisors that the numbers share. The greatest common factor (GCF) is the largest of these common factors.

Finding Factors

  • Start with 1 and the number itself
  • Test each integer from 2 to √n
  • If n ÷ i has no remainder, both i and n÷i are factors

Practical Applications

Fraction Simplification

Use GCF to reduce fractions to lowest terms

Example: 18/24 = (18÷6)/(24÷6) = 3/4

Problem Solving

Distribute items equally among groups

Example: Dividing pizza slices or inheritance

Number Theory

Foundation for understanding divisibility

Example: Prime factorization and modular arithmetic