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

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

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