2十4十6十8十．．．十18十20 2十4十6十8十...十50简便计算？
2\u53414\u53416\u53418\u5341\uff0e\uff0e\uff0e\u534118\u534120\u4e8c2\u53414\u53416\u53418\u5341\uff0e\uff0e\uff0e\u534118\u534120
=2\uff081+2+3+...+10\uff09
=\uff081+2+3+...+10\uff09+\uff0810+9+8+...+1\uff09
=\uff081+10\uff09+\uff082+9\uff09+\uff083+8\uff09+...+\uff0810+1\uff09
=11x10=110
2\u53414\u53416\u53418\u5341...\u534150\u7b80\u4fbf\u8ba1\u7b97\uff1a
\u89e3\uff1a2+4+6+8+...+50
=\uff082+50\uff09x25\u00f72
=52x25\u00f72
=650
\u6269\u5c55\u8d44\u6599
\u4e58\u6cd5\uff1a
1\uff09\u4e58\u6cd5\u4ea4\u6362\u5f8b\uff1aa*b=b*a
2\uff09\u4e58\u6cd5\u7ed3\u5408\u5f8b\uff1aa*b*c=\uff08a*b\uff09*c=a*\uff08b*c\uff09
3\uff09\u4e58\u6cd5\u5206\u914d\u5f8b\uff1a\uff08a+b\uff09*c=a*c+b*c\uff1b\uff08a-b\uff09*c=a*c-b*c
\u9664\u6cd5\uff1a
1\uff09\u55461653\u4e0d\u53d8\u7684\u6027\u8d28\u5373\u88ab\u9664\u6570\u4e0e\u9664\u6570\u540c\u4e58\u4ee5\u6216\u540c\u9664\u4ee5\u4e00\u4e2a\u6570\uff08\u96f6\u9664\u5916\uff09\uff0c\u5546\u4e0d\u53d8\u3002
a/b=\uff08a*n\uff09/\uff08b*n\uff09=\uff08a/n\uff09/\uff08b/n\uff09
2\uff09\u4e24\u4e2a\u6570\u7684\u548c\uff08\u5dee\uff09\u9664\u4ee5\u4e00\u4e2a\u6570\uff0c\u53ef\u4ee5\u7528\u8fd9\u4e2a\u6570\u5206\u522b\u53bb\u9664\u8fd9\u4e24\u4e2a\u6570\uff08\u5728\u90fd\u80fd\u6574\u9664\u7684\u60c5\u51b5\u4e0b\uff09\uff0c\u518d\u6c42\u4e24\u4e2a\u5546\u7684\u548c\uff08\u5dee\uff09\u3002
\uff08a+b\uff09/c=a/c+b/c\uff1b\uff08a-b\uff09/c=a/c-b/c
从两边相中间加，2+20，4+18，6+16，8+14，10+12，都是22，5个22，是110.（…省略的规律，要不就没答案了）
（2+20）X5 = 110
绛旓細瑙ｏ細2+4+6+8+...+96+98+100 =锛2+100锛墄50梅2 =102x25 =2550
绛旓細绫绘瘮浜庢褰紝鍏紡锛氾紙涓婂簳+涓嬪簳锛*楂/2 鍗2+4+6+...+18=锛2+18锛*9/2=90
绛旓細绠渚胯绠楁柟娉曪細2锛4锛6锛8锛10鈥︹︼紜20 =2+4+6+8+10+12+14+16+18+20 =锛2+20锛+锛4+18锛+鈥︹︼紙10+12锛=(2+20)脳10梅2 =110 鍒嗘瀽锛氳鏁板垪鏄竴涓瓑宸暟鍒,鍏樊涓2,棣栭」涓2,鍏辨湁10椤广傛墍浠,鍒╃敤绛夊樊鏁板垪鍓峮椤瑰拰鍏紡锛歋(n)=n*(a(1)+a(n))/2锛坣涓烘鏁存暟,an涓虹瓑宸暟鍒...
绛旓細锛2+20锛*5=110
绛旓細鍏紡锛氥愶紙鍓嶉」+鍚庨」锛壝楅」鏁懊2銆2+4+6+8+10+12+14+16+18+20锛濓紙2+20锛壝10梅2锛22脳10梅2锛220梅2锛110
绛旓細浜鍔狅紝鍥涘姞锛屽叚鍔狅紝鍏姞锛屽崄鍔狅紝12鍔狅紝14鍔狅紝16鍔狅紝18锛岀敤涓骞寸骇鐨勬柟娉曟潵璁＄畻锛屽叿浣撳涓嬶細瑙ｏ細2+4+6+8+10+12+14+16+18 =锛2+18锛+锛4+16锛+锛6+14锛+锛8+12锛+10 =20+20+20+20+10 =40+40+10 =80+10 =90 绛旓細绛変簬90銆
绛旓細2+4+6+8锛岄偅涓姞鍗佸姞鍔犲嚑鍔犲嚑鍔16+18+20锛岀敤绠渚挎柟娉曠畻銆 鎬诲叡10涓暟锛 涓や袱鍒嗙粍锛 2+20=4+18=鈥︹ 鎵浠ワ紝绛旀鏄 (2+20)脳10梅2 =22脳10梅2 =110 20鍑18鍔16鍑14,鍔12鍑10,鍗,鍔犲叓鑺,6鍔4鍑2杩欓亾棰樼敤绠渚挎柟娉曟庝箞璁＄畻? 20-18+16-14+12-10+8-6+4-2 =...
绛旓細锛2+16锛+锛4+14锛+锛6鍗12锛+锛8+10锛=18+18鍗l8+18=18脳4=72
绛旓細2鍗4鍗6鍗8鍗鈥︹﹀崄58鍗60=62脳15=930銆傚洜涓洪鍜屽熬涓ゆ暟2+60=62锛4+58=62锛6+56=62锛屸︹ 锛28+34=62锛30+32=62銆傗2鍗4鍗6鍗8鍗佲︹﹀崄58鍗60鈥濅竴鍏辨湁30涓暟鐩稿姞锛屾瘡涓や釜涓缁勶紝鏈15缁勶紝鍒欏氨鏈15涓62锛屾墍浠ュ拰涓62脳15=930銆
绛旓細2鍗4鍗6鍗8鍗...鍗50绠渚胯绠楋細瑙ｏ細2+4+6+8+...+50 =锛2+50锛墄25梅2 =52x25梅2 =650
