This work experimentally and numerically studies large deflection of slender cantilever beam of linear elastic material, subjected to a combined loading which consists of internal vertical uniformly distributed continuous load and external vertical concentrated load and a horizontal concentrated load at the free end of the beam. We got equations with the help of large deflection theory, and present the differential equation governing the behaviour of this system and show that that this equation, although straightforward in appearance, is in fact rather difficult to solve due to the presence of a non-linear term. A numerical evaluation is used to evaluate the system and calculate Young`s modulus of the beam material. With simple experiment we show, how a Young`s modulus can be obtained and then the phenomenon of the large elastic sideways deflection of a column under compressive loading is investigated and elastica of buckled column is calculated.