DECILES
The nine points on the scale of observations ( or values of the variable) which divide the total frequency into ten equal parts are called deciles for the data arranged in ascending or descending order of magnitude. When data are in ascending order the first point is called first decile and is denoted by D_{1} the second point is called second decile and is denoted by D_{2} and so on the last point is called ninth decile and is denoted by D_{9}.