The study considers sixteen functions of the first degree that were used for the analytical presentation of the aggregate size characteristics by "plus" of the Kuznetsk basin coal in the size range from 0 to 300 mm. The computational experiment was carried out for 500 aggregate coal size characteristics. The parameters of the functions were determined by the known method of least squares. When required, the formulas were reduced to a linear form. To solve systems of linear algebraic equations, the Cramer method was used in Excel (using the built-in function MDETERM () for calculating matrix determinants), Gauss method in the TurboPascal (reduction of matrices to a triangular form). The quality of the approximations was estimated by the value of the standard deviation between experimental and calculated values of the total yields (ash content) of the size classes. To carry out the computational experiment in TurboPascal, computer programs Gran16_V.pas have been developed -to calculate the total yields of classes and Gran16_A.pas for calculating the ash content of the same classes. It is established that the Pogosov formula is the best in comparison with the others, including, with the well-known functions of Rosin-Rammler and Goden-Andreev.