解: 99999??778+33333??666原式=99999??778+33333???222 =99999??778+99999??222 =99999???778+22222) =99999??0000 =9999900000
99999x77778+33333x66666=99999X77778+99999X22222=99999x(77778+22222)=99999X100000=9999900000