490-23-49-128
=498-(49+1+128+2+20)
490-(50+130+20)
=498-200
=298
245-125+355-175
=(245+355)-(125+175)
=600-300
=300
498-23-49-128 245-125+355-175 这两题怎样进行简便计算
490-23-49-128
=498-(49+1+128+2+20)
490-(50+130+20)
=498-200
=298
245-125+355-175
=(245+355)-(125+175)
=600-300
=300