(1).6.3×10.3=6.3×(10+0.3)=6.3×10+6.3×0.3=63+1.89=64.89
(2).0.98×3.2=3.2×(1-0.02)=3.2×1-3.2×0.02=3.2-0.064=3.136
(3).2.5×4.4×0.7=2.5×0.4×11×0.7=(2.5×0.4)×11×0.7=1×11×0.7=7.7
(4).5.8×8.5＋5.8×0.5＋5.8=5.8.×(8.5+0.5+1)=5.8×10=58
打得辛苦啊,