巧算72乘以78等于多少 巧算；78x72等于多少。立算式
\u5de7\u7b97\uff1b78x72\u7b49\u4e8e\u591a\u5c11.\u7acb\u7b97\u5f0f8*2=16\u662f\u672b\u5c3e\u4e24\u4f4d
7*\uff087+1\uff09=56\u662f\u524d\u4e24\u4f4d
\u6240\u4ee5\u4e3a5616
8*2=16\u662f\u672b\u5c3e\u4e24\u4f4d
7*\uff087+1\uff09=56\u662f\u524d\u4e24\u4f4d
\u6240\u4ee5\u4e3a5616
=(70+2)×(70+8)
=70×70+2×70+8×70+2×8
=70×(70+2+8)+2×8
=70×80+2×8
=5600+16
=5616
记住，这样首位相同，个位相加等于10的数相乘，就是这样:
72×78
=70×80+2×8
=5600+16
=5616
这种叫做“同头尾合十”。
直接笔算啊，又不是心算神童
绛旓細=(70+2)脳(70+8)=70脳70+2脳70+8脳70+2脳8 =70脳(70+2+8)+2脳8 =70脳80+2脳8 =5600+16 =5616 璁颁綇锛岃繖鏍烽浣嶇浉鍚岋紝涓綅鐩稿姞绛変簬10鐨勬暟鐩镐箻锛屽氨鏄繖鏍:72脳78 =70脳80+2脳8 =5600+16 =5616 杩欑鍙仛鈥滃悓澶村熬鍚堝崄鈥濄
绛旓細鎵浠ヤ负5616
绛旓細鍥
绛旓細72脳78+36脳44 =72脳(78+22)=72脳100 =7200 杩欓亾棰樼洰涔嶄竴鐪嬩粬浠殑鍏洜鏁颁笉鏄庢樉锛屼絾鏄渶瑕佺煡閬撶殑鏄72绛変簬36x2銆傞偅涔堣繖灏卞彲浠ヨ绠楀嚭瀹冧滑鐨勫叕鍥犳暟鏄72銆備竴鎻愬彇鍑烘潵锛岄偅涔堣绠楀氨绠鍗曚簡銆
绛旓細鏌愪簺鎶宸р濇垨鍙戠幇鈥滄煇绉嶈寰嬧濇潵鎻愰珮杩愮畻閫熷害銆傚锛氶熺畻锛15*15=225 25*25=625 35*35=1225 鍙戠幇瑙勫緥浜嗗惂锛侊紙鍓嶈呭崄浣+1锛*鍚庤呭崄浣 涓綅*涓綅 閭ｄ箞55*55=? 锛3025锛宸х畻锛1+2+3+4+5+5+6+7+8+9 =(1+9)+(2+8)+(3+7)+(4+6)+(5+5)=50 甯屾湜鑳藉浣犳湁甯姪锛
绛旓細绛変簬36脳156+36脳44=36脳锛156+44锛=36脳200=7200 鎵浠ョ粨鏋滅瓑浜7200
绛旓細26X6X40 =26X240 =26X24X10 =624X10 =10 鍏充簬 26X24 杩欑 鏂规硶锛氬墠鎻愶細 涓や綅鏁涔樹互涓や綅鏁 锛屽崄浣嶇浉绛夛紝涓綅浜掕ˉ锛堢浉鍔绛変簬10锛夋柟娉 鍓嶉潰 2X锛2+1锛 = 6 鍚庨潰 6X4 = 24 26X24 =624 鍐嶄緥濡 78 X 72 = 5616 7X锛7+1锛 = 56 2X8 = 16 5616 ...
绛旓細7銆佸阀濡欑殑骞虫柟鍜屽樊鍏紡棰樼洰锛璁＄畻78²-22²銆傚畠鐨勫阀濡欎箣澶勫湪浜庯紝搴旂敤骞虫柟鍜屽樊鍏紡锛屼篃灏辨槸璇达紝鍏紡78²-22²=(78+22)脳(78-22)锛岀畝鍖栦簡涔樻硶杩愮畻銆8銆宸鐢ㄥ掓暟鍏崇郴棰樼洰锛氳绠1/3+1/4銆傚阀濡欎箣澶勫湪浜庡埄鐢ㄥ掓暟鍏崇郴锛屽嵆1/3+1/4=(4+3)/(3脳4)锛屽皢鍒嗘暟鐨勫姞娉曡浆鍖栦负...
绛旓細78脳200=15600銆65脳78锛78鍗134脳78=78脳(65+134+1)=78脳200=15600銆宸х畻(绠绠)锛屽寘鎷涔樻硶锛岄櫎娉曠殑鍒嗛厤寰嬬粨鍚堝緥浜ゆ崲寰嬪姞娉曚氦鎹㈢粨鍚堢瓑銆傝繖闇瑕佸湪鏌愪釜绠楀紡涓壘鍑烘壘鍒颁簡鍙互搴旂敤鐨勫畾寰嬶紝鍙婃瘡涓暟鐨勫垎瑙ｆ暟锛屽氨鍙互宸у鍦扮畻鍑恒
绛旓細缁忔祹鏁板鍥㈤槦涓轰綘瑙ｇ瓟锛屾弧鎰忚閲囩撼锛299脳78 =锛300-1锛壝78 =300脳78-78 =23400-78 =23 322
