The full forms of L.C.M. and H.C.F are Least Common Multiple and Highest Common factor respectively.
HCF (Highest Common Factor)
According to the rule of arithmetic, the greatest common divisor of two or more positive integers is the largest positive integer that divides the numbers without leaving a remainder. For example, take 12 and 24. The H.C.F. of 12 and 18 will be 6 because the highest number that can divide both 12 and 8 is 6.
LCM (Least Common Multiple)
The least common multiple or LCM is the smallest or least positive integer that is divisible by both the number. LCM of two numbers say a and b, is denoted as LCM (a,b) then the least positive number should be divisible by both a and b. For example, let us take two positive integers 12 and 18. The L.C.M. of 12 and 18 will be 36 because the least positive number that is divisible by both 12 and 8 is 6.