4.86× 9.9
=4.86×10-4.86×0.1
=48.6-0.486
=48.114
4.9×1.02
=5×1.02-0.1×1.02
=5.1-0.102
=4.998
3.84乘以9.6+0.96乘以61.6
=3.84×9.6+9.6×6.16
=9.6×（3.84+6.16）
=9.6×10
=96