小数四则混合运算专项练习276题(有答案)

1、能简算的要简算呦，加油，你是最棒的！小数混合运算专项练习276题（有答案）(1)0.11X1.8+8.2X0.11(9)1.8X(3.41-2.9)+0.03(2)2.34X99+2.34(10)0.125X32X2.5.(3)5.4+2.7X0.8(11)1.258X18.50.258X18.5(4)132X101(12)8.48+0.8X0.9小数混合运算-1(13 )1.25 X2.4(5)6.25+1.25+0.8(6)2.5X16.(14)5.85+(1.3+0.5)X6.6.33X1016.33(15)17.176.83.26.17(8)1.56X1.7+0.44X1.7(16)5

2、.4X(1.3+2.15)+0.2(17 )8.4+0.6+8.4 +0.4(25 )83.7 12.83 0.17(18 )16.8 X 10.1(26)5.96+13X(3.2-3.12)小数混合运算-3(19)10.90.9+0.2+1.8(27)4.32+2.4X1.7;(20)1.25X3.2X0.25.(28)16.2X4.5+3.8X4.5;(21)1.36+4.85+2.64+6.15(29)9.05-3.863.14;(22)98.5+2.5+4(30)7.28+0.72+0.9(23)5.4+2.5X(3.7-2.9)314.32+5.43+6.68(24)0.8X(43.

3、68)+0.01(32)17.17-6.8-3.2(33 )5.29X 9+5.29(41)15.68- ( 7.78 4.32) - 2.32小数混合运算-#(34)16.8X10.1(42)0.25X3.2X1.25(43 )9.99X1.01(35)2.74X9.5+5X0.274(36 )0.36+9.6 + 3.2.(44)4.63X1.4+46.3X0.86(37)3.75X25+6.25X25(45)17.5+0.8+12.5(38)25.46-8.23-1.76(46)0.9+9.9+99.9+999.9.(47 )2.9X 99+2.9(39)2.9+7.1X10(48 )2

4、5X 11.2X4(40)1.25X32X0.25.(49 )23.25- 6.75- 3.25.(57 )35.6-5X 1.73小数混合运算-5(50)125X3.2X2.5(58)1.6X55.455.4X0.6(51)3.6X10.1(59)17.68+5.2+2.7X1.5.(52)5.8X2.7+0.58X73(60)1.08X0.8+0.27(53)3.6+6.4X1.8(61)102X0.4554(1.48+3.02)+(3.6X0.5)(62)22.78+1.25+0.855(36.74.9)X10131.8.(63)0.34X1010.34.(56)6.33X1016.33

5、(64)0.125X32X2.5(65 )0.8X 6.3- 0.8X 3.8(73 )10.8-0.8- ( 0.35+0.05 )(66 )504+3.2X2.08(74)8X1+(2.3-2.25)小数混合运算-7(75 )2.64X9.9+0.264(67)(200.8X9)X5.7(68)2.4X1.5+3.6+1.5(76)4.52+0.61+1.39+6.48(69)7.38-5.14+3.622.86(77)4.27(1.961.73)(70 )0.12X 1.8+8.2X 0.12(78)(294.4-19.2X6)+(6+8)(71) 5.4+0.51+(1.21.03)(

6、79)12.5X0.76X0.4X8X2.5.(80)4.98+8.02 X 2.5(72) (8.15.6)X0.9T.05+0.04.(81)60.8 40.8+2.5(89 )7.236-0.18- 14.3X0.02.小数混合运算-#(82)0.8X69.6X12.5(90)9.6+0.4X0.25(83 )4.98X99+4.9(91) 29.7+(5.85+0.65)(92 )7.4X 9.9(84)6.48+3.2+2.5(85)1.2X7.6+7.6X6.8.(93)3.84-2.7X0.64(86)(9.45.8)X2.07(94)8.688.68+0.56X0.5(92)

7、12.54-4.56-3.44-1.54(95) 4.7X4.7+4.7+4.3X4.7.(88) (9.36X5+9.36+9.36X2)X1.25(96) 2.72+(8.26.5)X0.5;(97 )9.12+9.12 X 9 60.2 ;(105)11.87- ( 8.2+1.87)(98)28.4+0.4+0.25;(106) 5.423.871.13小数混合运算-9(99)27.3627.36+7.6.(107) 4.38-1.56+0.620.44(100)3.25X0.45+6.75X0.45(108)0.4X270X2.(101)31.524.5+3.5(109)(40+1.

8、25)X8(102)7.5X102(110)(12.50.05)X8(103)6.3+3.7X2.8.(111)2.6X8.5+8.5X7.41042.15+8.73+1.27+7.85(112)9.9X6.96.9X3.9(113 ) 5.6X 99+5.6(121) 0.25X1.25X 3.2(114)2.5X(1.9+1.9+1.9+1.9)(122)6.4X14+15X6.4+6.4小数混合运算-11(115 )7.2+1.25 + 8.(116 ) 52.4- (15+0.6) + 1.6(124) 4X ( 25+2.5+0.25) + 111(123)(1.3+1.3X0.12

9、5X8)+(8077.4)(117) 9.87X 99+9.87(125)6.25+(17.23.6X4.5)+0.32(126) 28.4X99+28.4(118)46.8+0.9+0.4(119)5.5X 17.3+6.7 X 5.5.(127)0.94X2.5- 0.45(120) 99X4.2+4.2(128)4X0.8X12.5X2.5(129 )17.5-0.25X 17+13.(137)7.5 (5.5+1.24)(130 )10.1X87(138)0.26+15.68+9.74+2.32小数混合运算-#(139)13.26+9.55 - 3.26(131)2.3+3.19+(2

10、219.8)(132)1.25X 7.2.(140)6.1+3.9-6.1+3.9.(133 ) 9.1 1.2+66.24(141)31.7+0.63(保留2位小数)(134)7.3+12.8-3.8X2.3(142)2.4X1.5+3.6+1.5(135) (5.36+7.64)+13X100(143)0.32X0.25+0.08+4(144)(9.6+1.48 + 3.7) +8(136) 7.575+(5.631.88)X0.2.(145) 5.8 + 4 X (1.34 0.14)(153)(45+14) + 73+710.(154)13.7 X 0.125 X 8(147)21.3

11、5 3.25 16.75(155)0.8 X 13 - ( 3.12+5.28(148) 33.02 - ( 148.4 - 90.85 ) + 2.5(156)102X 0.56(149) 32X 2.5 X 0.125(157)1.53 X 1.7+0.47 X 1.7 .(150) 18.1+ (3 0.299 +0.23 ) X 1.158)5.18+0.73+0.82(151)67- ( 2.98+0.67 )(159)0.75 X 1.8 + 1.5(152)8X 16 73.8 X6(160)12.5 X7.1 X 0.8(146)5.4+0.51+(1.21.03).小数混合运

12、算-13(177)(2.5+27.75 + 1.5 ) X 1.6 .(185)64X4.5+3.6X45(162)8.6 +0.86+8 X 0.35(170)91 + 2.6 +0.05=(171)6.3 X 3.7+6.3 X6.3=(163)5.6X(18.58.5+0.5)(164)0.125 X4.78 X 80(172)(3.7+1.7X0.4)+2.5=(165)2.8 X 3.6+1.4 X 2.8(173)7.28+3.2 +2.5=(166)(0.4+40 ) X 2.5(174)0.74+0.9 X 7.4=(167)78.7 17.7 X 3.6(175)7.8 +

13、0.125 + 0.8=(168)18+ 0.3 X (86.5)(176)37.5 + 0.3 X ( 1.34 0.84)(178)6.21 3.8+2.2(186)1.25X3.2X0.8(179) 6.03+3.7+2.97(187)14.5X102188)14.64+3.7 2.8(181)20.47 - ( 1.47+6.8)(189)8.4+0.21 + 0.5.182)13.26+4.71+3.47+5.29(183)22.74+8.68 13.74.(190)0.125X 9X 8X 0.3(184)10+0.2 + 2.5(191)4.62 + 5+0.66(180) 17

14、.43-6.57-2.43小数混合运算-15(192)5.78X 2.3+5.78+5.78 X 6.7(200)18.2 - 10.6 X ( 0.9 0.75 )(201)0.25 X3.85 X 40(194) 1.25X 0.5X8X 0.2(202) 1.46 X3.5+3.5 X 4.54 .(195)0.97X 9+0.97(203) 7X 12.5X 0.8(193) 7.75X20-(3.243.04).小数混合运算-#(204)4.7 X 3.6+4.7X 6.4(197)0.4 X ( 3.2 0.8 ) + 0.15(205)1.45 X (2.8+4.4) +2.4.

15、(198) 5.7+1.9 X 0.2+7.6(206) 4.2 X ( 6.18 3.03 ) +6.3(199)32.4 X 6.3+32.4 X 3.7(207) 15.02 - 6.8 - ( 1.02+1.2 )(196) 5.4+3X(3.82.9).(208)0.6 X (5 0.68 ) +1.2(216)2.7 X 1.5 - 2.7(209) 2.7 +4+6.3 X 0.25(217)9.08+5.45+11.92+4.55(210) (6.02+2.8 ) - 0.4 - 2.05(218) 1.25 X30X 1.2 X 0.8 .(219) 3.08 X 3.5+6

16、.2 X 3.08+3.08 X 0.3 .(219)0.6+0.94 - 0.208(212) 2.3+3.91 - (22- 19.7)(220)4.85X1.25X8(213)21.6+ 64.8 (48.6 2.7X 2).(221)(64 22.4+ 1.4) X 1.2(214)93.6 X 3.6+1.4 X 3.6(222)18.3-6.25- 3.75(223)2.8X 3.6+1.4X 2.8(215) 0.25X0.8X0.125X0.4小数混合运算-17(224)6.6+ 14.5 ( 1.7+1.8)(232) (7.6 5.2 ) + 0.4+2.54X 32.(2

17、25)0.25 X 9.87 X4(233) 17.68+5.2+2.7 X 1.5(226)36.7 X 2.1 + 10.8(234) 35.6-5X 1.73(227) 8.45 0.45 X 0.1(228) 0.73 X 102(237)1.08 +1.8 X 1.2(238)50.4 X 1.9 - 1.8235) )(1.10.78)X(2.7-1.236) 1.30.754(229) 7.8X5.6+2.3X4.4(230) 76.3X27-76.3X17.小数混合运算-#(231) 7.05X23.7+7.05X76.3.(239) 0.82X0.25+1.18X0.25.(

18、240)8.5X(2.36+2.42)+0.25(248)8X(20-1.25)(241)3.9+(1.3+0.6)X63.6(249)0.654+10.9X6.5(242)4.25X6.3+3.7X4.25(250)22.7X1.25X0.8小数混合运算-19243)205 0.99(251)3.91X2.8+6.09X2.8.(252)6.23+3.09=(244) 25.6-7.49-2.51(253)132.4- 59.8=(245) 2.5(6.84.9)X0.8.(246)102X4.5(254)6.62X0.84=(255)2.07 + 0.023=(247) 3.4+(1.2+

19、0.5)X5(256)20.026(8.6+9.7)X0.92+30.19.(264)2.5X99+2.5;(257)0.125X32X2.5(265)10.36+4.8-16.5-5;(258)0.8X6.3-0.8X3.8(266)12.5X2.4.(259)50.4+3.2X2.08(267)38.78-19.59+41.22-30.41(260)204+(3.4X0.5)(268)2.74X4.86+4.86X6.26+4.86(261)(43.26+2.34)+7.5(269)0.08X(12.5+2.5)X0.1262)(200.8X9)X5.7.(270)25.92+(10.1-

20、14.5X0.2)(263)13.250.8+1.75-1.2;(271)0.487X12.5+48.7小数混合运算-21(272)(8.16+2.09 ) + (10.3 -9.3) + 0.4.(275)0.25 X 2010+20.10 X 75(273)1.56 X 1.7+0.44 X 1.7(276)30.8+(6.344.59)X4.小数混合运算-(274) 12.5X(7.21.9)X0.8参考答案：(1) 0.11X1.8+8.2X0.11,=0.11X(1.8+8.2),=0.11X10,=1.1;(2) 2.34X99+2.34,=2.34X(99+1),=2.34X10

21、0,=234;(3) 5.4+2.7X0.8,=2X0.8,=1.6;(4) 132X101,=132X(100+1),=132X100+132,=13332;(5) 6.25+1.25+0.8,=6.25+(1.25X0.8),=6.25+1,=6.25;(6) 2.5X16,=(2.5X4)X4,=406.33X101-6.33,=6.33X(101-1),=6.33X100,=633;(8) 1.56X1.7+0.44X1.7,=1.7X(1.56+0.44),=1.7X2,=3.4;(9) 1.8X(3.412.9)+0.03,=1.8X0.51+0.03,=1.8X17,=30.6;

22、(10) 0.125X32X2.5,=(0.125X8)X(4X2.5),=1X10,=10(11) 1.258X18.5-0.258X18.5,=18.5X(1.258-0.258),=18.5X1,=18.5;(12) 8.48+0.8X0.9,=10.6X0.9,=9.54;(13) 1.25X2.4,=1.25X8X0.3,=10X0.3,=3；(14) 5.85+(1.3+0.5)X6,=5.85+1.8X6,=3.25X6,=19.5(15) 17.17-6.8-3.2-6.17=(17.17-6.17)-(6.8+3.2),=1110,=1；(16) 5.4X(1.3+2.15)

23、+0.2=5.4X3.45+0.2,=5.4X17.25,=93.15;(17) 8.4+0.6+8.4+0.4=14+21=35;(18) 16.8X10.1=16.8X10+16.8X0.1,=168+1.68,=169.68;(19) 10.9-0.9+0.2+1.8=10.9-4.5+1.8,=8.2;(20) 1.25X3.2X0.25=(1.25X0.8)X(4X0.25),=1X1,=1(21) 1.36+4.85+2.64+6.15,=(1.36+2.64)+(4.85+6.15),=4+11,=15;(22) 98.5+2.5+4,=98.5+(2.5X4),=98.5+10

24、,=9.85;(23) 5.4+2.5X(3.7-2.9),=5.4+2.5X0.8,=5.4+2,=2.7;(24) 0.8X(4-3.68)+0.01,=0.8X0.32+0.01,=0.256+0.01,=25.6;小数混合运算-0(25) 83.7 - 12.83 - 0.17 , =83.7 - ( 12.83+0.17 ), =83.7 - 13, =70.7 ;(26) 5.96+13 X ( 3.2 - 3.12 ), =5.96+13 X0.08 , =5.96+1.04 , =7.(27) 4.32 +2.4 X 1.7 ,=1.8 X 1.7 ,=3.06 ;(28) 1

25、6.2 X4.5+3.8 X 4.5 ,=(16.2+3.8 ) X 4.5 ,=20X4.5 ,=90;(29) 9.05 - 3.86 -3.14 ,=9.05 - ( 3.86+3.14 ),=9.05 - 7,=2.05 ;(30) 7.28+0.72 +0.9, =7.28+0.8 , =8.08(31) 4.32+5.43+6.68 ,=4.32+6.68+5.43 ,=11+5.43 ，=16.43 ;(32) 17.17 - 6.8 -3.2 ,=17.17 - (6.8+3.2 ),=17.17 - 10,=7.17 ;(33) 5.29 X 9+5.29,=5.29 X (

26、 9+1),=5.29 X 10,=52.9 ;(34) 16.8 X 10.1 ,=16.8 X 10+16.8 X 0.1 ,=168+1.68 ,=169.68 ;(35) 2.74 X 9.5+5 X 0.274 ,=2.74 X 9.5+0.5 X 2.74 ,=2.74 X ( 9.5+0.5 ),=2.74 X 10,=27.4 ;(36) 0.36+9.6 + 3.2,=0.36+3 ,=3.36(37) 3.75 X 25+6.25 X 25,=25X ( 3.75+6.25 ),=25X10,=250;(38) 25.46-8.23-1.76,=25.46-(8.23+1.

27、76),=25.46-9.99=15.45;(39) 2.9+7.1X10,=2.9+71,=73.9;(40) 1.25X32X0.25=(1.25X8)X(4X0.25),=10X1,=1.(41) 15.68-(7.78-4.32)-2.32,=15.68-7.78+4.32-2.32,=(15.68+4.32)-(7.78+2.32),=20-10,=10;(42) 0.25X3.2X1.25,=0.25X4X0.8X1.25,=(0.25X4)X(0.8X1.25),=1X1,=1;(43) 9.99X1.01,=(10-0.01)x1.01,=10.1-0.0101,=10.089

28、9;(44) 4.63X1.4+46.3X0.86,=46.3X0.14+46.3X0.86,=46.3X(0.14+0.86),=46.3X1,=46.3;(45) 17.5+0.8+12.5,=17.5+(0.8X12.5),=17.5+1,=17.5;(46) 0.9+9.9+99.9+999.9,=1-0.1+10-0.1+100-0.1+1000-0.1,=(1+10+100+1000)-(0.1+0.1+0.1+0.1),=1111-0.4,=1110.6(47) 2.9X99+2.9=(99+1)X2.9,=100X2.9,=290;(48) 25X11.2X4=25X4X11.

29、2,=100X11.2,=1120;(49) 23.256.753.25小数混合运算-25=23.25 - ( 6.75+3.25 ),=23.25 - 10,=13.25(50) 125X 3.2 X 2.5 ,=125X 8X 0.4 X 2.5 ,=(125X8) X ( 0.4 X2.5 ),=1000X 1,=1000;(51) 3.6 X 10.1 ,=3.6 x (10+0.1 ),=3.6 x 10+3.6 x 0.1 ,=36+0.36 ,=36.36 ;(52) 5.8 X 2.7+0.58 X 73,=5.8 X 2.7+5.8 X 7.3 ,=5.8 X ( 2.7+7

30、.3 ),=5.8 X 10,=58;(53) 3.6+6.4 X1.8,=3.6+11.52 ,=15.12 ;(54) (1.48+3.02 ) + ( 3.6 X 0.5 ),=4.5 + 1.8 ,=2.5 ;(55) (36.7 - 4.9 ) X 101 -31.8 ,=31.8 X 101 - 31.8 ,=31.8 X ( 101T),=31.8 X 100,=3180(56) 6.33 X 101 - 6.33=6.33 X ( 101T),=6.33 X 100,=633;(57) 35.6 - 5X 1.73 ,=35.6 - 8.65 ,=26.95 ;(58) 1.6

31、 X 55.4 - 55.4 X 0.6 ,=55.4 X ( 1.6 - 0.6 ),=55.4 X 1 ,=55.4 ;(59) 17.68 +5.2+2.7 X 1.5 ,=3.4+4.05 ,=7.45(60) 1.08 X 0.8 +0.27=1.08 +0.27 X 0.8 ,=4X 0.8 ,=3.2 ;(61) 102X0.45=(100+2) X 0.45 ,=100X0.45+2X0.45,=45+0.9,=45.9;(62) 22.78+1.25+0.8=22.78+(1.25X0.8),=22.78+1,=22.78;(63) 0.34X101-0.34=(101-1)

32、X0.34,=100X0.34,=34(64) 0.125X32X2.5,=(0.125X8)X(4X2.5),=1X10,=10;(65) 0.8X6.3-0.8X3.8,=0.8X(6.3-3.8),=0.8X2.5,=2；(66) 504+3.2X2.08,=157.5X2.08,=327.6;(67) (20-0.8X9)X5.7,=(20-7.2)X5.7,=12.8X5.7,=72.96(68) 2.4X1.5+3.6+1.5,=3.6+2.4,=6；(69) 7.38-5.14+3.62-2.86,=(7.38+3.62)-(5.14+2.86),=118,=3；(70) 0.1

33、2X1.8+8.2X0.12,=0.12X(1.8+8.2),=0.12X10,=1.2;(71) 5.4+0.51+(1.21.03),=5.4+0.51+0.17,=5.4+3,=1.8;(72) (8.15.6)X0.9-1.05+0.04,=2.5X0.9-1.05+0.04,=2.25-1.05+0.04,=1.2+0.04,=30(73) 10.8-0.8-(0.35+0.05),=10.8-0.8+0.4,=10.8-2,=8.8;(74) 8X1-(2.3-2.25),=8X1-0.05,=8X20,=160;(75) 2.64X9.9+0.264,=0.264X99+0.26

34、4,=0.264X(99+1),=0.264X100,=26.4;(76) 4.52+0.61+1.39+6.48=(4.52+6.48)+(0.61+1.39),=11+2,=13;(77) 4.27-(1.96-1.73)=4.27-0.23,=4.04;(78) (294.4-19.2X6)+(6+8)=(294.4-115.2)+14,=179.2+14,=12.8;(79) 12.5X0.76X0.4X8X2.5=(12.5X8)X(0.4X2.5)X0.76,=100X1X0.76,=76.(80) 4.98+8.02X2.5,=4.98+20.25,=25.03;(81) 60.

35、8-40.8-2.5,=60.8-16.32,=44.48;(82) 0.8X69.6X12.5,=(0.8X12.5)X69.6,=10X69.6,=696;(83) 4.98X99+4.9,=493.02+4.9,=497.92;(84) 6.48-3.2-2.5,=6.48+(3.2X2.5),=6.48+8,=0.81;(85) 1.2X7.6+7.6X6.8,=7.6X(1.2+6.8),=7.6X8,=60.8(86) (9.4-5.8)>2.07,=3.6X2.07,=7.452;(87) 12.54-4.56-3.44-1.54,=(12.54-1.54)-(4.56+3

36、.44),=11-8,=3；(88) (9.36X5+9.36+9.36>2)XI.25,=9.36X(5+2+1)XI.25,=9.36>8XI.25,=9.36X(8X1.25),=93.6;(89) 7.2360.18-14.3X).O2,=40.2-0.286,=39.914.(90) 9.6-0.4X0.25,=24X0.25,二6;(91) 29.7十(5.85-0.65),=29.7+9,=3.3;(92) 7.4X9.9,=7.4X(10-0.1),=7.4X10-7.4X0.1,=74-0.74,=73.26;(93) 3.84-2.7X0.64,=3.84-1.

37、728,=2.112;(94) 8.688.68-0.56X0.5,=8.68-15.5X0.5,=8.68-7.75,=0.93;(95) 4.7X4.7+47+4.3X4.7,=4.7X(4.7+4.3+1),=4.7X10,=47(96) 2.72-(8.2-6.5)X0.5=2.72-1.7X0.5,=2.72+0.85,=3.2;(97) 9.12+9.12X9-60.2=(1+9)X9.12-60.2,=10X9.12-60.2,=91.2-60.2,=31；(98) 28.4-0.4-0.25=28.4+(0.4X0.25),=28.4-0.1,=284;小数混合运算一2(99)

38、 27.36 - 27.36 +7.6 =27.6 - 3.6 , =24(100) 3.25 X 0.45+6.75 X 0.45 , =0.45 X ( 3.25+6.75 ), =0.45 X 10, =4.5 ;(101) 31.5 24.5 +3.5 ,=31.5 - 7,=24.5 ;(102) 7.5 X 102, =7.5 X (100+2), =7.5 X 100+7.5 X 2, =750+15, =765;(103) 6.3+3.7 X2.8, =6.3+10.36 , =16.66 .(104) 2.15+8.73+1.27+7.85 =(2.15+7.85 ) + (

39、8.73+1.27 ), =10+10, =20;(105) 11.87 ( 8.2+1.87 ), =11.87 - 1.87 - 8.2 , =10 - 8.2 , =1.8 ;(106) 5.42 - 3.87 - 1.13 ,=5.42 - 5, =0.42 ;(107) 4.38 - 1.56+0.62 - 0.44 , =(4.38+0.62 ) - ( 1.56+0.44 ), =5-2, =3；(108) 0.4 X 270X2.5 , =(0.4 X 2.5 ) X 270, =270;(109) (40+1.25 ) X 8,=40X 8+1.25 X 8,=320+10,

40、 =330;(110) (12.5 0.05 ) X 8,=12.5 X 8-0.05 X 8,=100-0.4 , =99.6 ;(111) 2.6 X 8.5+8.5 X 7.4 , =(2.6+7.4 ) X 8.5 , =85;(112) 9.9X6.9-6.9X3.9,=(9.9-3.9)X6.9,=6X6.9,=41.4;(113) 5.6X99+5.6,=5.6X(99+1),=560;(114) 2.5X(1.9+1.9+1.9+1.9),=2.5X4X1.9,=10X1.9,=19;(115) 7.2+1.25+8,=7.2+8+1.25,=0.9-1.25,=0.72.(1

41、16) 52.4-(15+0.6)+1.6,=52.4-15.6-1.6,=52.4-9.75,=42.65;(117) 9.87X99+9.87,=9.87X(99+1),=987;(118) 46.8+0.9+0.4,=46.8+(0.9X0.4),=46.8+0.36,=130;(119) 5.5X17.3+6.7X5.5,=5.5X(17.3+6.7),=5.5X24,=132(120) 99X4.2+4.2=4.2X(99+1),=4.2X100,=420;(121) 0.25X1.25X3.2=0.25X1.25X(4X0.8),=0.25X4X(1.25X0.8),=1X1,=1

42、；(122) 6.4X14+15X6.4+6.4=6.4X(14+15+1),=6.4X30,=192;(123) (1.3+1.3X0.125X8)+(80-77.4)=(1.3+1.3X1)+2.6,=2.6+2.6,=1；(124) 4X(25+2.5+0.25)+111=(4X25+4X2.5+4X0.25)+111,小数混合运算-29=(100+10+1)+111,=111+111,=1;(125) 6.25-(17.23.6X4.5)+0.32=6.25+(17.2-16.2)+0.32,=6.25+(1+0.32),=6.25+3.125,=2(126) 28.4X99+28.4

43、,=28.4X(99+1),=28.4X100,=2840.(127) 0.94X2.5-0.45,=2.35-0.45,=1.9.(128) 4X0.8X12.5X2.5,=(4X2.5)X(0.8X12.5),=10X10,=100.(129) 17.5+0.25X17+13,=70X17+13,=1190+13,=1203(130) 10.1X87,=(10+0.1)X87,=87+8.7,=95.7;(131) 2.3+3.19-(22-19.8),=2.3+3.19+2.2,=2.3+1.45,=3.75;(132) 1.25X7.2,=1.25X8X0.9,=10X0.9,=9(1

44、33) 9.1-1.2+6-6.24=9.1-0.2-6.24,=8.9-6.24,=2.66;(134) 7.3+12.83.8X2.3=20.1-8.74,=11.36;(135) (5.36+7.64)+13X100=13+13X100,=100;(136) 7.575-(5.631.88)X0.2=7.575+3.75X0.2,=7.575+0.75,=10.1(137) 7.5(5.5+1.24),=7.5-5.5-1.24,=2-1.24,=0.76;(138) 0.26+15.68+9.74+2.32,=(0.26+9.74)+(15.68+2.32),=10+18,=28;(1

45、39) 13.26+9.55-3.26,=13.26-3.26+9.55,=10+9.55，=19.55;(140) 6.1+3.9-6.1+3.9,=6.1-6.1+(3.9+3.9),=0+7.8,=7.8(141) 31.7+0.6350.32;(142) 2.4X1.5+3.6+1.5=3.6+2.4,=6；(143) 0.32X0.25+0.08+4=0.08+0.08+4,=0.08+0.02,=0.08+0.02,=0.1;(144) (9.6+1.48+3.7)+8=(9.6+0.4)+8,=10+8,=1.25;(145) 5.8+4X(1.34-0.14)=5.8-4X1.

46、2,=5.8+4.8,1.21;(146) 5.4+0.51+(1.21.03)=5.4+0.51+0.17,=5.4+3,=1.8(147) 21.35-3.25-16.75,=21.35-(3.25+16.75),=21.35-20,=1.35;(148) 33.02-(148.4-90.85)+2.5,=33.0257.55+2.5,=33.02-23.02,=10;(149) 32X2.5X0.125,=4X8X2.5X0.125,=(4X2.5)X(8X0.125),=10X1,=10;(150) 18.1+(3-0.299+0.23)X1,=18.1+(3T.3)X1,=18.1+

47、1.7X1,=18.1+1.7,=19.8(151) 67-(2.98+0.67),=67-3.65,=63.35;(152) 8X16-73.8X6,=128+442.8,=570.8;(153) (45+14)+73+710,=59+73+710,=2710,73=71073(154) 13.7X0.125X8,=13.7X(0.125X8),=13.7X1,=13.7;(155) 0.8X13(3.12+5.28),=0.8X13-8.4,=0.8X4.6,=3.68;(156) 102X0.56,=(100+2)X0.56,=100X0.56+2X0.56,=56+1.12,=57.1

48、2;(157) 1.53X1.7+0.47X1.7,=(1.53+0.47)X1.7,=2X1.7,=3.4(158) 5.18+0.73+0.82-=(5.18+0.82)+0.73,=6+0.73,=6.73;(159) 0.75X1.8+1.5,=1.35+1.5,=0.9;(160) 12.5X7.1X0.8,=(12.5X0.8)X7.1,=10X7.1,=71；(160) 6.12X99+6.12,=6.12X(99+1),=6.12X100,=612;(162) 8.6+0.86+8X0.35,=10+2.8,=12.8;(163) 5.6X(18.58.5+0.5),=5.6X(18.5-17),=5.6X1.5,=8.4(164) 0.125X4.78X80,=0.125X4.78X8X10,=(0.125X8)X(4.78X10),=1X47.8,=47.8;(165) 2.8X3.6+1.4X2.8,=2.8X(3.6+1.4)