整数乘法的运算定律推广到小数.ppt
整数乘法的运算定律 推广到小数,乘法交换律,乘法结合律,a×b=b×a,(a×b)×c=a× (b×c),乘法分配律,(ab)×c=a×cb×c,a× (bc)=a×ba×c,=,(2.43.6) ×0.5 2.4×0.53.6×0.5,=,=,乘法交换律,乘法结合律,乘法分配律,整数乘法的交换律、结合律和分配律,对于小数乘法也适用。,0.25×3.57×4 3.57× (_×_) 2.63×0.5× 4 _× (_× _) 0.75×(200+1) _×_ _ 6.7×0.70.3×6.7_×(_),0.25 4,2.63 0.5 4,0.75 200 0.75,6.7 0.7 0.3,0.034×0.5×0.6,102×0.45, 0.034×(0.5×0.6), 0.034×0.3, 0.0102,(1002) × 0.45, 100×0.452×0.45, 45 0.9, 45.9,乘法结合律,乘法分配律,2.5×0.73×4, 0.73×(2.5×4), 0.73×10 7.3,(1.252.5)×8, 1.25×82.5×8, 1020 30,乘法交换律,乘法结合律,乘法分配律,7.2×997.2, 7.2×(991), 7.2×100 720,0.25×12, 0.25×(4×3), 0.25×4×3 1×3, 7.2×997.2×1, 3,乘法结合律,乘法分配律,0.125×32×0.25,(0.125×8)×(0.25×4), 1×1 1, 0.125×(8×4)×0.25,乘法交换律,乘法结合律,98×6.5 (982)×6.5 100 ×6.5 650,12.5×2.5×3.2 12.5×2.5×(8×0.4) 12.5×82.5×0.4 1001 101,这样算对吗?如果不对,错在那里?,乘法分配律,乘法交换律,乘法结合律,