Could someone help me understand why this program is using a static method and what it does?

public class MylavaLab05 fanction for add.sabtract and so on static double addNambersidouble xdouble y) statie doable sabtractNumbers doubles double y) return x-y static double multiplyNumbers double x double y) static double divideNumbers doublk x doubk y static doable poweNumbers deuble x double y) fenen Math pow(yk start pregram function tatic void startPeogram) double numl.num char ch Scanner se- new Scannen System ink do while loop System out printinl"Welcome to working with Nambers System out printin Please enter two mumbers: System.outprintin Number 1 num1 se.nextDouble System.outpristinl"Number 2 menaOptionsnum m2 System.out printin Would you like so keep weeking with Numbensy ch-sc.nest charAuO datic void menaOptionsldouble x double y) int choice double res Scanner sc-new Scannen Systom ink System.out pristin Please select a mea option below: System out prsln(" Calculate " +s+-..+yk Syslemout predn(-4 Calculate "+s+" / " Sysem.outpratIn("S.Calculale "+X-^-3% choice sc.nextln) switchichoice res divideNumbersis y)k default System out printin Tevalid menu option