Number Tools
Find the greatest common divisor and least common multiple of two numbers, check whether a number is prime, or list all of its factors.
Factors, prime numbers, the greatest common divisor (GCD) and the least common multiple (LCM) are the building blocks for simplifying fractions and ratios, finding common denominators and working out when repeating events coincide.
These tools work with positive whole numbers and show the method alongside the result.
Calculators in this category
Which calculator do I need?
- What are the factors of 360? The Factors Calculator lists every factor of a whole number up to 1,000,000,000,000.
- Is 97 a prime number? The Prime Number Checker tests a whole number up to 1,000,000,000,000.
- What are the GCD and LCM of 24 and 36? The GCD and LCM Calculator gives both for two positive whole numbers.
Good to know
1 is not a prime number, and 2 is the only even prime.
The GCD of two numbers multiplied by their LCM equals the two numbers multiplied together: for 24 and 36, 12 × 72 = 864 = 24 × 36. The factors and primes guide explains how each is found and used.
Background reading
- Factors, primes, GCD and LCM Finding factors and primes, prime factorisation, and how the greatest common divisor and least common multiple simplify fractions and solve scheduling problems.