125×99+79脱式=125x(100-1)+79=125x100-125+79=12500-46=12454 489-232-68脱式,=489-(232+68)=489-300=189
125*(100-1)+79=12500-125+79=12500-(125-79)=12500-46=12454 489-(232+68)=489-300=289