The least square method is based on the assumption that the past rate of change of the variable under study will continue in the future. It is a mathematical procedure for fitting a line to a set of observed data points in such a manner that the sum of the squared differences between the calculated and observed value is minimized. This techniques is used to find a trend line which best it the available data. This trend is then used to project dependant variable in the future. This method is very popular because it is simple and in expensive.