Free Factoring Calculator — GCD, LCM & Prime Factorization

A factoring calculator breaks numbers down into their fundamental components using three powerful modes: GCD (Greatest Common Divisor) via the Euclidean algorithm, LCM (Least Common Multiple), and prime factorization via trial division. Each mode shows the complete step-by-step process so you can follow the logic from input to answer.

Factoring is a building block of number theory and practical arithmetic alike. Whether you're simplifying fractions (GCD), finding common denominators (LCM), or breaking a number into its prime components, this calculator does the heavy lifting while teaching you the method behind each result.

• Greatest Common Divisor (GCD) - Find the largest number that divides two or more values evenly, essential for simplifying fractions
• Least Common Multiple (LCM) - Determine the smallest number divisible by all inputs, crucial for adding fractions with different denominators
• Prime factorization - Decompose any integer into its prime factors expressed with exponents
• Factor breakdown - See the complete list of prime factors and how many times each appears
• Step-by-step algorithm - Follow the Euclidean algorithm or trial division process move by move
• Dual display - View results as both a factor list and exponential notation (e.g., 2³ × 3² × 5)

• Simplifying fractions requires GCD - To reduce a fraction to lowest terms you need the greatest common divisor of numerator and denominator, which isn't always obvious
• Common denominators require LCM - Adding or subtracting fractions with different denominators means finding the least common multiple, which gets harder with larger numbers
• Large numbers are hard to factor - Trial division by hand becomes extremely tedious as numbers grow, especially when factors aren't small primes
• Algorithms have multiple steps - The Euclidean algorithm requires repeated division and remainder tracking, making it easy to lose your place

Select your mode — GCD, LCM, or prime factorization — and enter your numbers. For GCD, the calculator applies the Euclidean algorithm, showing each division and remainder until the remainder reaches zero. For LCM, it uses the relationship LCM(a,b) = |a×b| / GCD(a,b). For prime factorization, it uses trial division, testing each potential prime factor and recording how many times it divides evenly.

Every step is displayed in order so you can trace the entire algorithm from start to finish. The final result is presented in both expanded and exponential notation.

Example

Entering 360 in prime factorization mode produces: 360 ÷ 2 = 180, 180 ÷ 2 = 90, 90 ÷ 2 = 45, 45 ÷ 3 = 15, 15 ÷ 3 = 5, 5 ÷ 5 = 1. The result is 2³ × 3² × 5, meaning 360 = 2 × 2 × 2 × 3 × 3 × 5.

• Fraction simplification - Use GCD(24, 36) = 12 to reduce 24/36 to 2/3 instantly
• Adding fractions - Use LCM(4, 6) = 12 to find the common denominator for 3/4 + 5/6
• Cryptography basics - Prime factorization is the foundation of RSA encryption and related algorithms
• Scheduling problems - Use LCM to find when two cyclic events will coincide again
• Number theory homework - Verify factor trees, GCD calculations, and LCM results step by step

• Three modes in one tool - GCD, LCM, and prime factorization without switching between different calculators
• Full algorithm trace - Every division step, remainder, and factor extraction is displayed clearly
• Exponential notation - Results shown as prime factors with exponents for clean, standard mathematical form
• Educational value - Learn the Euclidean algorithm and trial division by watching them execute on your numbers
• Free and unlimited - Factor as many numbers as you want with no sign-up or usage restrictions

What modes does the calculator support?

The calculator offers three modes: GCD (Greatest Common Divisor), LCM (Least Common Multiple), and prime factorization. Each mode has its own input format and step-by-step output.

What algorithm is used for GCD?

The GCD mode uses the Euclidean algorithm, which repeatedly divides the larger number by the smaller and takes the remainder until the remainder is zero. The last non-zero remainder is the GCD. Every step is shown.

Is there a limit on number size?

The calculator handles numbers within standard computational precision, which covers integers up to trillions. For everyday math, school assignments, and most practical applications, this range is more than adequate.

What is prime factorization used for?

Prime factorization is used to simplify fractions, find GCD and LCM, analyze divisibility, and forms the mathematical basis of modern cryptography. It's also a core topic in number theory courses.

Does the LCM calculation show the GCD step?

Yes. Since LCM is computed using the formula LCM(a,b) = |a×b| / GCD(a,b), the calculator first computes the GCD with full steps, then shows how it's used to derive the LCM.

Is this calculator free?

Yes, the factoring calculator is completely free to use. All three modes are available with no limits on the number of calculations.