75×99+75 =75×(99+1) =75×100 =7500 83×102-83×2 =83×(102-2) =83×100 =8300 31×870+13×310 =31×870+130×31 =31×(870+130) =31000 123×43-43×23 =43×(123-23) =43×100 =4300 50×(34×4)×3 =50×4×34×3 =200×102 =20400 35×37+65×37 =37×(35+65) =37×100 =3700 38×29+38 =38×(29+1) =38×30 =1140 123×57-57×23 =57×(123-23) =57×100 =5700 124+78+22 =124+(78+22) =124+100 =224
