四年级数学下册 小数乘法简便计算

四年级数学下册 小数乘法简便计算


简介:
(1)25.4×1.25×0.8 =25.4×(1.25×0.8) =25.4×1 =25.4 (2)3.6×10.1 =3.6×(10+0.1) =3.6×10+3.6×0.1 =36+0.36 =36.36 (3)5.74×29-5.74×19 =5.74×(29-19) =5.74×10 =57.4 (4)8×(12.5-0.125) =8×12.5-8×0.125 =100-1 =99 (5)2.31×1.2×0.5 =2.31×(1.2×0.5) =2.31×0.6 =1.386 (6)99×4.3 =(100-1)×4.3 =100×4.3-4.3 =430-4.3 =425.7