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1、六年级奥数专项精品讲义常考题汇编-计算问题一小数的巧算一.选择题1.计算15.1+16.1+17.i+.23.1=()A.171.1B.152.8C.172D.1522.己知=0.00088,力=0.0004,那4+力=()2005个02006个0A.0.00.012B.0.00.0922005个02005个0C.0.00012D.0.000922006个02006个O二.填空题3 .计算3.45X0.1+0.5X34.5+0.049X345=.4 .0.0.0560.0014=.2i9个02019个05 .2.00539020.0541+200.52=.6 .计算:6.250.16+2640
2、.0625+5.26.25+0.62520=.7 .已知如图,贝JAB=.A=0.00.096,B=0.00.03.200个02院个08 .232.14+64.280.53780.25+0.537864.280.75-864.280.1250.5378=.9 .小明求得某7个自然数的平均数等于30.26,后来发现这个小数的小数点后的最后一位数是错误的.则这7个自然数的平均值应约等于.(结果保留到小数点后两位)10 .0.000.00480.000.0016=.2009个2009个三.计算题11 .7.85-2.3+4.15-4.712 .下面各题,能简算的要用简便方法计算.43x10.21.2
3、5 320.251.26 2.43+1.4317.8-3.8617.89812,50.813 .8.32.5+31.72.514 .用简便方法算一算.(1)0.2512.50.480(3)9.70.0425015.简便计算1.250.90.80.221012.58.8+2.51.216 .12.5x2.5x0.3217 .用简便方法计算.17.4837-174.81.9-1.74880;9997+l1137.18 .用你喜欢的方法计算0.25320.1252817.5-287.519 4+3.65.2四.解答题19. 2.50.875+0.251.2520. 0.1+0.2+0.3+.0.90
4、.10+0.11+.0.980.99.21. 0.11+0.120.13.0.180.19(以最简分数表示)22. 计算:(1+0.12+0.23)(0.12+0.23+034)-(1+0.12+0.23+0.34)(0.12+0.23)=66.617.6+3340.24+13.3638=998877+988776+887766+877665+776655+766554+665544+655443=(l234.910l1)(2827252422)=1.23452+0.76552+2.469x0.7655=23. 用简便方法计算(1) 0.9999x0.7+0.1111x2.7;(2) (1+0
5、.228-0.21)(0.228-0.21+0.2003)-(1+0.228-0.21+0.2003)(0.228-0.21)24. 3.17+7.48-238+0.53-3.48-1.62+5.3.25. l640.1250.0250.05.26. 1.725+2.7253.725+.+50.725.六年级奥数专项精品讲义常考题汇编-计算问题一小数的巧算参考答案一.选择题1 .解:15.1+16.1+17.1+.23.1,=15-+16-+17-+.+23-,9999=(15+16+17+.23)H99=(15+23)92+l,=3892+l,=171+1,=172;答案:C.2 .解:0.
6、00.088+0.00.04=0.00.0922005个O2006个02005个0答案:B.二.填空题3 .解:3.450.1+0.534.5+0.049345=3.450.1+53.45+4.93.45=3.45(0.1+54.9)=3.4510=34.5答案:34.54 .解:0.0.0560.001420何个02013个0=0.0.056x10000.0014x10002019个02021个02019个02021个0=5614=4答案:4.5 .解:2.00539020.0541+200.52=20.0539+20.0541+20.0520=20.05100=2005答案:2005.6
7、.解:原式=6.25x0.16+2.64x6.25+5.2x6.25+6.25x2,=6.25x(0.16+2.64+5.2+2),=6.25x10,=62.5.故答案为62.5.7 .解:0.00.0960.00.03,2007个O2006个O=96300,=0.32;答案:0.32.8 .解:232.14+64.280.53780.25+0.537864.280.75-864.280.1250.5378,=232.14+64.280.5378(0.25+0.75-80.125),=232.1464.28X0.5378X0,=232.14.答案:232.14.9 .解:因为这个这个小数的小数
8、点后的最后一位数是错误的,所以答案就有可能在30.21-30.29之间,30.267=211.82,211+7*30.14不符合题意212+730.29题意符合,故答案为30.29.10 .解:000000048000000161 IIA120092009个=48*16=3三.计算题11 .解:7.85-2.3+4.15-4.7=(7.854.15)-(2.3+4.7)=512 .解:(1)4.310.2=4.3(10+0.2)=4.310+4.30.2=43+0.86=43.86(2) 1.25320.25=(1.258)(40.25)=10l=10(3) 17.82.43+1.4317.8
9、-3.8617.8=17.8(2.43+1.43-3.86)=17.80=O(4) 9812,50.8=98(12,50.8)=9810=9.813.解:8.32,531.72.5=2.5(8.3+31.7)=2.540=10014.解:0.2512,50.480=(0.250.4)(12.580)=0.110=100(2)3.7x2.75+2.75x6.3=(3.7+6.3)2.75=10x2.759.70.04250=9.7(0.04250)=9.710=0.9715.解:1.25x0.9x0.8=1.25x0.8x0.9=0.9(2) 0.22101=0.22x(100+1)=0.221
10、00+0.22=22.22(3) 2.58.8+2.51.2=2.5(8.8+1.2)=2.5x10=2516.解:12.5x2.5x032=12.52.50.40.8=(12.50.8)(250.4)=IOxl=1017 .解:(1)17.4837-174.81.9-1.74880=17.4837-17.4819-17.488=17.48x(37-19-8)=17.48x10=174.8.9997+lll37=11163+11137=lll(63+37)=lll100=IllOO.18 .解:(1)0.25320.125=(0.254)(80.125)=11=1(2) 2817.5-287.
11、5=28(17.5-7.5)=2810=280(3) 6.4+3.65.2=6.4+18.72=25.12四.解答题19 .解:2.50.875+0.25l.25=2.5x0.875+2.5x0.125=(0.875+0.125)2.5=12.5=2.520 .解:0.1+0.2+0.3+.+0.9+0.100.11+.0.98+0.99=(0.1+0.9)92+(0.1+0.99)902=4.5+1.0945=4.5+49.05=53.5521 .解:0.11+0.12+0.13.0.18+0.191011121718=+F+909090909010+11+.+18二90(10+18)92二
12、90=7522.解:(1)设Q12+0.23=x,0.12+0.23+0.34=y,则:(1+0.12+0.23)(0.12+0.23+0.34)-(I+0.12+0.23+0.34)(0.12+0.23)=(l+x)y-(l+)x=y+xyxxy=y-x=(0.12+0.23+0.34)-(0.12+0.23)=0.34;(2) 66.617.6+3340.2413.3638=6661.76+3340.24+(3340.04)38=6661.76+334(0.24+1.52)=6661.76+3341.76=(666+334)1.76=10001.76=1760(3) 998877+9887
13、76887766+877665+776655766554665544655443=(998877+655443)+(988776+665544)+(887766+766554)+(877665+776655)=16543204=6617280;(4) (l234.910ll)(2827252422)_123456789IOxll47395538211=4;(5) 1.23452+0.765522.4690.7655=(1+0.2345)(1+0.2345)+(1-0.2345)(1-0.2345)+2(1+0.2345)(1-0.2345)=1.2345(1+0.2345)+(1-0.2345)+0.7655(1-0.2345)+(1+0.2345)=1.23452+0.76552=2(1.2345+0.7655)=423 .解:0.9999x0.7+0.1111x2.7=(0.1111x9)x0.7+0.1111x2.7=0.11116.3+0.11112.7=0.111l(63+2.7)=0.1111