145+263+155-298的简便脱式计算
问题描述:
145+263+155-298的简便脱式计算
答
145+155-(298-263)=300-35=265
答
145+263+155-298
=145+155+253-298
=300+253-298
=553-(300-2)
=553-300+2
=253+2
=255