346+128+254
=(346+254)+128
=600+128
=728
599-133-248
=599-(133+248)
=599-381
=218
345+234+245
=345+245+234
=690+234
=924
8X3-3X2
=3×（8-2）
=3×6
=18
187-65-87
=187-87-65
=100-65
=35
108-7X4
=27×4-7×4
=4×（27-7）
=4×20
=80
用递等式计算（能巧算的要巧算） 346+128+254 599-133-248 345+234+245 8X3-3X2