What is LCF?
Please see below.
I am sure you meant LCM and not LCF, as there is no term like that in mathematics. (The Lowest Common Factor would always be 1)
GCF stands for greatest common factor. You list out all the factors of given numbers and then list common factors (common factors among all the numbers). The greatest among them is GCF. There are plenty of examples, if you make search on Socratic.
As factors are less than the numbers, GCF is always less than or equal to smallest numbers.
LCM stands for least common multiple. You list out large enough number of multiples of given numbers and then list common multiples. The least of them is Least Common Multiple. Again one can find plenty of examples on Socratic for this.
As multiples are greater than or equal to the numbers, LCM is always greater than or equal to largest number.
One interesting thing is that if only two numbers are there, product of their GCF and LCM is equal to product of the two numbers.