LCM stands for Lowest Common Multiple, and HCF stands for Highest Common Factor.
The LCM of two integers is the smallest whole number that appears in both of their times tables, that is, the smallest integer that is a multiple of both numbers.
For example, the LCM of 4 and 6 is 12.
The HCF of two integers is the largest whole number that divides both numbers without leaving a remainder.
For example, the HCF of 16 and 32 is 16.