用简便方法计算 0.28×8.6+7.2×0.86 和999×778+333×666 怎样写?
问题描述：
用简便方法计算 0.28×8.6+7.2×0.86 和999×778+333×666 怎样写?
答
0.28×8.6+7.2×0.86
=2.8×0.86+7.2×0.86
=0.86×(2.8+7.2)
=0.86×10
=8.6
999×778+333×666
=999×778+999×222
=999×(778+222)
=999×1000
=999000