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Factors of any number, with the working

Type a number to see all its factors, its factor pairs and its prime factorisation step by step. Free, no login.

HCF and LCM calculatorFactors of 1 to 100Prime numbers to 1000Divisibility rules

What this site does

Factors, primes, HCF and LCM make up one of the most used chapters of school maths, from class 5 to class 10 and again in every competitive exam. The ideas are simple, but the working must be set out step by step, and that is where marks are lost. This site shows the steps.

The factor finder above takes any whole number up to a million million. It lists the factors and factor pairs, shows the prime factorisation as a division ladder, counts the factors from the powers, and says whether the number is prime, a perfect square, perfect, abundant or deficient. The HCF and LCM calculator does the same for two to six numbers, by three methods.

Factors of the numbers people look up most

Each of these has its own page, with the working by hand, the divisibility tests applied to that number, and HCF and LCM examples.

Learn the chapter

Common questions

What is a factor?

A factor of a number is a whole number that divides it exactly. The factors of 12 are 1, 2, 3, 4, 6 and 12.

How do I find all the factors of a number?

Divide the number by 1, 2, 3 and so on up to its square root. Each exact division gives two factors: the divisor and the answer.

What is the difference between HCF and LCM?

The HCF is the largest number that divides all the given numbers. The LCM is the smallest number that all of them divide. For 12 and 18 the HCF is 6 and the LCM is 36.

Is 1 a prime number?

No. A prime has exactly two factors, and 1 has only one. It is neither prime nor composite.

More maths from our family: Tables for multiplication tables, and Worksheets for printable HCF and LCM practice with answers.