数学几百几十的加减法.ppt

单击此处编辑母版标题样式,,单击此处编辑母版文本样式,,第二级,,第三级,,第四级,,第五级,,,*,几百几十的加减法（一）,九年制义务教育小学数学,第四册,,,1,．拆数游戏,,,,（,1,）把下面各数拆成整百和整十数,,,360,，,480,，,520,，,790,，,210,，,630,,,,（,2,）把下面各数拆成整百和一百几十的数,,,360,，,720,，,270,，,450,，,840,，,980,2,．口答,,,（,1,）,320,是由几个百和几个十组成的？,,（,2,）,320,是由几个十组成的？,,（,3,）,32,是由几个十几个一组成的？,3,．口算,,,（,1,）,20+40+300=,（,2,）,300+400+20=,,（,3,）,60-20+300=,（,4,）,300-200+60=,,320 + 40 =,,6,300,20,360,20加上40得60，,,300加上60得360．,,360,－,40,=,,７,300,60,320,,练一练,160＋30= 230＋40=,,,,190－30= 270－40=,,,,60＋120= 180－60=,,320,+,400,=,,８,300,20,720,720,－,400,=,,20,320,700,,练一练,（,1,）,150+300=,,240+400=,,450-300=,,,640-400=,,700+210=,,810-700=,,,（,2,）,410+50=,,770-600=,,280-60=,,,630+200=,,300+370=,,490-80=,（,3,）,,1,．每张卡片上两个数的和是多少？差是多少？,,140 40,,350 200,,440 300,,560 30,,650 40,,360 200,2,．看谁算得又对又快.,,210+80= 360-200= 550-40=,,400+450=,,30+260= 630-200= 620-300= 720+40=,,40+430= 760-60=,,190+200= 890-80=,,25+47=,,300+570= 700-400= 87-75=,,。