①积的变化规律
②小数的性质
③转化策略
④乘法分配律
20×30 0.2×0.3
=(2×10)×(3×10) =(2×0.1)×(3×0.1)
=(2×3)×(10×10) =(2×3)×(0.1×0.1)
=6×100 =6×0.01
=600 =0.06