怎么简便算法5.2×3.7+10.4×2.1+0.52×21=5.2×3.7+5.2×4.2+5.2×2.1=5.2×(3.7+4.2+2.1)=5.2×10=52
5.2*3.7+10.4*2.1+0.52*21=5.2*(3.7+2*2.1+2.1)=5.2*10=52
5.2×3.7+10.4×2.1+0.52×21=5.2×3.7+5.2×2×2.1+5.2×2.1=5.2×(3.7+4.2+2.1)=5.2×10=52