I would like to get the administration's response as the fractional part is rounded growth abilities sailors using boost:

in big side  30.2=31 ,

in less side 30.2=30,

or by the rules of rounding math - if the fractional part is less than 5, then rounding occurs in less side 30.2=30, if the fractional part is equal to or greater  than 5,then the option of rounding up the side 30.5=31,

or differently?