FactorsWhat the calculator shows
- Prime factorisation. Each number is written as a product of primes. The HCF takes the shared primes with their smallest powers, and the LCM takes every prime with its largest power.
- Division method. Euclid's method for the HCF, one division per line, in the form "dividend = divisor × quotient + remainder".
- Common division. The ladder used in school for the LCM of several numbers.
- A check. For two numbers it confirms that HCF × LCM equals their product.
How to use it for homework
Work the sum yourself first, then type the numbers and compare line by line. If your answer differs, the working shows where. Copying an answer teaches nothing, but finding your own slip teaches a lot. Teachers can use it to make a checked worked example in a few seconds.
Which method should I write in the exam?
Use the one your question names. If it names none: for two large numbers the division method is shortest; for three or more numbers, common division is the usual choice for the LCM and prime factorisation gives both answers at once.
Limits
Each number can be up to 1,000,000,000. The common division ladder is shown when every number is 1,000,000 or less. The numbers you type stay in your browser and are not sent anywhere.
Learn the methods
HCF by three methods, LCM by three methods, Euclid's algorithm, solved word problems and HCF and LCM of fractions.