奥数题 简便计算
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发布时间：2022-09-15 13:18
共1个回答
热心网友
时间：2023-10-09 04:55
=315×(7×11×13)
=315×1001
=315315
67×31+31×85+152×69
=31×(67+85)+152×69
=31×152+152×69
=152×(31+69)
=152×100
=15200
79×8181-81×7979
=79×81×101-81×79×101
=0
6666×6666
=3×2222×3333×2
=(2222×2)×(3333×3)
=4444×9999
=4444×(10000-1)
=4444×10000-4444
=44440000-4444
=44435556
15×213÷27+15×327÷27
=15÷27×(213+327)
=15÷27×540
=15×(540÷27)
=15×20
=300
1+2-3+4+5-6+7+8-9+……-97+98-99
=1+(2-3)+(4-5)+(6-7)+......+(96-97)+(98-99)
=1+(-1)+(-1)+(-1)+......+(-1) (49个-1)
=1-49
=-48
999×222+333×334
=333×3×222+333×334
=333×666+333×334
=333×(666+334)
=333×1000
=333000
164×166-163×167
=(165-1)×(165+1)-(165-2)×(165+2)
=(165²-1²)-(165²-2²)
=165²-1-165²+4
=3
19941994×1995-19951995×1994
=1994×10001×1995-1995×10001×1994
=0
66…… 6×99…… 9
=66......6×(100......0-1) (100个0)
=66......6×100......0-66......6
=66......600......0-66......6 (100个0,100个6)
=66......6533......34 (99个6,99个3)
1+2-3-4+5+6-7-8+9+10-……+1990
=1+(2-3-4+5)+(6-7-8+9)+......+(1986-1987-1988+1989)=+990
=1+0+0+......+0+1990
=1991
76000÷1 00……0×2 00……0
=76000÷(100......0÷200......0)
=76000÷50
=1520
243×247-242×248
=(245-2)×(245+2)-(245-3)×(245+3)
=(245²-2²)-(245²-3²)
=245-4-245+9
=5
不懂可追问，望采纳，谢谢！追问这啥啊……和我要的完全不一样啊……
