Calculation of limits is a main topic in calculus, which gives us the value of the function as x approaches a particular real value. We are already familiar with different ways of calculating limits of functions, by direct substitution, eliminating holes, by substitution, rationalization etc. In this section we are going to evaluate the limit of the function as x approaches either from the left or from the right. This helps us to examine the continuity of the function at the given point. Further this also helps us if the given function is differentiable at a given point.