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529.ա)  30x(99004-98914):300=3

                  1)99004-98974=30
                 2)30x 30=900
                 3)900:300=3

                200x(6000-5960)x80=64000

                 1)          6000
                            — 5960
                          ______

                                040
                 2)  200×40=8000
                 3)8000X80=640000

             բ)   300:(77004-76944)x50=250

531  ա) 30000+147+160000+153=(30000+160000)+(147+153)=190000+300=190300
               2400+600+20+180=(2400+600)+(20+180)=3000+200=3200
                 52418+200+20+180=(52418+200)+(20+180)=52618+200=52818

        բ) 350+20000+7000+150=(350+150)+(20000+7000)500+27000=27500
                   3700+300+90+410=(3700+300)+(90+410)=4000+500=4500
              43700+300+90+410=(43700+300)+(90+410)=44000+500=44500

612. ա) 12×5=10×5=2×5=60                     բ)18×6=10×6=8×6=108    
               22×4=20×4+2×4=88                          27×3=20×3+7×3=81
               5×42=5×40+5×2=210                        4×22=4×20+4×2=88