From Mathisfun! Find all the factors of a number or use their Prime Factorisation Tool.
WolframAlpha queries:
Find all the factors of a number
Write a number as a product of its prime factors
Highest common factor (greatest common divisor) of two numbers
Lowest common multiple of two numbers
Math Playground – Factors
On Math Playground you can learn how to use factor trees to write a number as a product of its prime factors, also to find the HCF and LCM of two numbers.
The highest common factor (GCF) of 24 and 100 is 4 (2×2)
and the lowest common multiple is 600 (2×3×2×2×5×5)
(Note that you can select Help for explanations).
Mathematics for Students 