人教版四年級數(shù)學下冊簡便計算.ppt
簡 便 計 算,復習:下面各題怎樣算簡便就怎樣算。,78X25X4,=78X(25X4) =78X100 =7800,125X27X8,= 27X( 8X125) =27X1000 =27000,600 25 4,=600 (25 X4) =600100 =6,7000 8 125,=7000 (8 X125) =70001000 =7,25x12,12x25,12x25 =(3x4)x25 =3x(4x25) =3x100 =300(元),12x25 =12x100 4 =1200 4 =300(元),12x25 =(10+2)x25 =10 x25+2x25 =250+50 =300(元),12x25 =12x (20+5) =12 x20+12x5 =240+40 =300(元),12x25 =(6x2) x 25 =6 x(2x25) =6x50 =300(元),12x25 =12x(5x5) =(12 x5)x5 =60 x5 =300(元),32x25,每枝羽毛球拍多少錢?,330 5 2,330 (5x2),16x125,16x125 =(2x8)x125 =2x(8x125) =2x1000 =2000,16x125 =16x1000 8 =16000 8 =2000,24x125,35x16,125x32x25,35x16 =35x2x8 =70 x8 =560,35x16 =7x(5x16) =7x80 =560,125x32x25 =125x(8x4)x25 = (125x8)x(4x25) =1000 x100 =100000,口算:,25x16,12+57+880,28x25,36x17+ 64x17,103-24-76,125x24,28x25x4,36x25,