简算:990+891+792+693+594+495+396+297+198+99

来源:学生作业学帮网 编辑:学帮网 时间:2024/05/31 00:43:56

简算:990+891+792+693+594+495+396+297+198+99

990+891+792+693+594+495+396+297+198+99 =990+(891+99)+(792+198)+.+495 =990*5+495 =5445 990+891+792+693+594+495+396+297+198+99 =99*10+99*9+.+99*1 =99*(10+9+8+.+1) =99*55 =5445