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Prime Factorization

Enter a whole number from 2 and see its prime factorization written as a product of prime powers. The result follows the usual school method: trial division by primes, then exponents for repeated factors. Useful alongside GCD/LCM work and for checking factor trees.

Whole number ≥ 2 (e.g. 360 for class practice).

How it works

Enter a whole number from 2 and see its prime factorization written as a product of prime powers. The result follows the usual school method: trial division by primes, then exponents for repeated factors. Useful alongside GCD/LCM work and for checking factor trees.


The Formula

Every integer n > 1 can be written uniquely (up to order) as
n = p1^a1 × p2^a2 × … × pk^ak
where each pi is prime and each ai is a positive whole number.

Worked Example

  1. Example: 360

    360 ÷ 2 → 180 ÷ 2 → 90 ÷ 2 → 45, then 45 ÷ 3 → 15 ÷ 3 → 5, then 5 ÷ 5 → 1. So 360 = 2^3 × 3^2 × 5^1. The tool prints that compact form and how many distinct primes appear.


Tips, Assumptions & Limitations

  • Start from the smallest prime (2) and divide until it no longer fits, then try 3, 5, 7, and so on.
  • If n is prime, the factorization is just n^1.
  • Use the total count of prime factors (with multiplicity) when work asks for “how many prime factors.”
FAQ

GCD finds the largest shared divisor of two numbers. This tool breaks one number into its prime building blocks. You often use prime factors first, then read off GCD and LCM by comparing exponents.

No. Prime factorization is defined for integers greater than 1. The tool asks for a whole number from 2 upward so the mathematics stays standard.

Very large integers make trial division slower in the browser. The cap keeps the page responsive while still covering typical coursework and practise values.

Use it to check factor trees or divisor lists you did by hand. Teachers usually want your steps; this confirms the final product-of-primes form.

Companion article

Prime Factorization Explained: Product of Primes Calculator

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How this calculator works

Prime factorisation (UK spelling) or prime factorization (US) is a core skill from middle school through GCSE and early algebra: rewrite an integer as a product of primes raised to powers. This article outlines the idea without heavy jargon and points to our calculator page for fast, transparent checks once you understand the rule.

Explanation

A prime number has exactly two positive divisors—1 and itself. The Fundamental Theorem of Arithmetic says every integer n > 1 can be written uniquely as a product of primes if you ignore order. Powers save space: repeated division by the same prime becomes an exponent, so structured answers match textbook mark schemes in both metric-first UK courses and typical US curricula.

Formula

For primes p1,…,pk and positive integers a1,…,ak: n = p1^a1 × p2^a2 × … × pk^ak. Uniqueness means there is only one multiset of primes and exponents that works for each n.

Worked example

Take 360. Divide out 2 until it no longer fits: 360 → 180 → 90 → 45, so three factors of 2. Then 45 ÷ 3 → 15 → 5 gives two factors of 3. Finally 5 is prime. Hence 360 = 2³ × 3² × 5. The exponent line is what many examiners expect after a factor tree.

How to use this tool

Open the Prime Factorization calculator, type one whole number ≥ 2 in the Positive integer box, then read the printed lines: the product-of-primes string with caret exponents, how many distinct primes appear, and the total prime factors counted with multiplicity (adds duplicate primes like the three copies of 2 in 360). If you leave decimals, negatives, or values under 2, you will see a plain-English correction instead of a result.

Frequently asked questions

Is factorisation spelling wrong if I write factorization?
Both spellings are normal—factorisation is common in the UK; factorization is common in the US. The mathematics is identical.
Can primes have more than one factorization?
Only the order may change—e.g. 2×3×5 or 5×2×3. The set of primes and their exponents is unique for n > 1.
How does this help with LCM and GCD?
Write two numbers in prime-power form, then take the minimum exponent for each prime for GCD and the maximum for LCM. Our GCD and LCM & HCF pages build on that idea.

Read the full guide →

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