72X36X28=(100-28)X36X28=3600X28-36X28X28=3600X28-36X(30-2)X28=360X280-360X84+36X56=360X(280-84)+36X(60-4)=360X(200-4)+2160-144=72000-1440+2160-144=72000+2160-1584=72000+2160-1600+16=72000+576=72576
72×36×28=72×28×36=2016×36=72576