第一篇:小数的简便计算
小数的简便计算
例
1、比较大小
(1)2.6×1.01()2.6×0.99(2)0.55×7.1()7.1
练一练、比较下面几组数据的大小
2.86×2.12 2.12×1.82 1.82 1.82×0.99
例
2、列竖式计算
(1)6.17+5.79(2)7.2-6.45(3)2.65×2.2
例
3、乘法分配律
(1)0.25×40.4(2)88.8×8.7+11.2×9.9-11.2×1.2
练一练、0.25×40.4+0.125×10.8
例
4、积不变定律
(1)3.7×46.9+0.37×531(2)199.7×19.98-199.8×19.96
例
5、凑整法
(1)0.9+9.9+99.9+999.9(2)9.8+99.8+999.8+9999.8
例
6、换元法
(1+0.12+0.23)×(0.12+0.23+0.34)-(1+0.12+0.23+0.34)×(0.12+0.23)
第二篇:小数简便计算
小数简便计算
1.135+3.346+5.557+7.768+9.979 1.996+19.97+199.8
9.8+99.8+999.8+9999.8+99999.8 2.894.68+4.686.11+4.68
1.1+3.3+5.5+7.7+9.9+11.11+13.13+15.15+17.17+19.19
6.11+9.22+8.33+7.44+5.55+4.56+3.67+2.78+1.89
17.4837-17.4819+17.4882 1.250.322.5
28.6767+32286.7+573.40.05 754.7+15.925
172.46.2+27240.38 0.88812573+9993
0.00…01810.00…011 34.58.23-34.5+2.7734.5
963个0 1028个0
下面有两个小数:
a=0.00…0105 b=0.00…019
1994个0 1996个0 求a+b,a-b,ab,ab.12.34+23.45+34.56+45.67+56.78+67.89+78.91+89.12+91.23
6.250.16+2640.0625+5.26.25+0.62520
19.9837-199.81.9+19980.82
0.035935+0.035+30.035+0.07610.5
13.59.9+6.510.1 19.9837-199.81.9+19980.82
32.14+64.280.53780.25+0.537864.280.75-864.280.1250.5378
第三篇:简便计算小数
加法结合律:
1.83+3.97+0.17
10-0.34-0.66
2.1+3.5+7.9+6.5
63.97-4.63-7.37
乘法结合律:
2.5X(1.32x0.4)
12.5x(3.4x0.8)
2.5x4.4
53.37+15.69-13.37
80x4.76x125
0.25x1.25x4x8
0.125x8.8
4.78+6.47-3.78
28x1.25x8 2.5x2.8x4x5 0.125x32
2.5x1.6
12.5x3.2x2.5
0.25x6.4x12.5
1.25x32x0.5
乘法分配律:
3.8x9.9+3.8x0.1
1.4x3.6+3.6x8.6
56.9x99+56.9
3.5x46+46x6.5
(12.5-1.25)x0.8 4.56x9.9+45.6 3.26x10.7-3.26x0.7
2.5x(4+0.4)0.35x199+0.35
3.2x0.64+0.32x3.6
5.2x9.8
0.45x102
3.7x9.9 0.78x101
第四篇:小数简便计算
五年级小数简便计算
156.5-21.7-3.3-6.5
36.8-8.21+2.21
12.5×32×2.5
10.1×56
4.5×45+4.5×54+4.5
12.5×0.32×2.5
9.98×6.2
0.32×45+0.32×54+0.32
12.5×8.08
2.5×(33×44)
(0.13+0.13+0.13+0.13)×0.25
9.9×9.9+0.99
(0.125+0.25)×0.8
0.27×45+2.7×5.5
65×9.9+6.5
2.5×1.3×0.4
0.25×0.32×1.25
(2.5+0.25)×0.4
0.98×1.02
12.5×80.8
4.6×4.6+6.4×4.6-4.6
1.3×2.5+0.13×75
9.9×9.9+0.99
8.08×12.5
9.9×101-9.9
1.6×3.7×1.25
7.23×9.8
16.4÷0.2512÷0.25
100÷0.25×0.8
0.125×25×1.6
6.46×7.7+12.3×6.46 7.14-3.95+2.86-1.05 7.6×8.1+0.19×76
5.9×1.6+5.9×0.4
9.9×2.8
(6.78+6.78÷6.78-6.78)×6.78
70÷1.25
45.55-(6.82+15.55)
1.08×125
2.18÷2.5÷0.4
10.8×9.6+92×0.96
1.7÷0.4÷0.25
3.8×0.25÷0.38
7.1÷(0.25×0.71)
18.4-2.7-7.3-2.4
17.2-2.2+3.3-3.8
6.4-6.4×0.56-6.4×0.34
9.98×3.7
4.7×0.9+0.47
3.54×7.7+3.3×3.54-3.5415÷1.25
12.5×8.08
13.2-4.6+6.8-5.4
4.31×0.99
5.9×59+5.9×36+5×5.9
81.3-2.38-7.62
2.74×6.5-2.74+4.5×2.74
1.2÷1.25
(3.1+3.1+3.1+3.1)×2.5
7.4-7.4×0.7-7.4×0.2
2.5×4.04
1.25×3.2×0.25
7.92+3.08-3.54-6.45
7.13×0.5+7.13+8.5×7.13
9.9×2.8+28×0.01
8.8×1.25×0.2
(3.7×4.6+4.3×4.6)×12.5
第五篇:小数的简便计算
小数的简便计算
(二)例一 计算
(1)45×1.4
(2)25×18×6
例二 计算
6.5×4.7+0.13×47+0.47×22
例三 计算0.999×0.7+0.111×2.7
例四 计算 12×(6.4÷9.3)÷(3.2÷3.1)
例五计算9.8÷0.25+0.2×4
同步练习1.计算
(1)2.65×1.7+13.5×0.17
2.计算
(1)2.65×1.7×13.5×0.17
4计算
(1)(8.2÷7.6)÷(4.1÷1.9)
2)2.5×14 2)111×3.6-0.2×333(2)8×1.7-0.7÷0.125((5、0.2÷(0.2÷0.3)÷(0.3÷0.4)÷(0.4÷0.5)÷(0.5÷0.6)÷(0.6÷0.7)÷(0.7÷0.8)
拓展
1、选择比较简便的方法计算下面各题
(1)99×23
(2)10.1×3.4
(3)(125-1.25)×0.8
(4)(7.7+15.4)÷7
(5)1.25×3.2×2.5
(6)9.8×(3.8+2.2)+6×0.2
2、填一填
4÷0.25=4×()
2.3÷0.125=2.3○8 7.2×()=7.2÷0.5
2×0.125=2○8 a÷()=a×()a÷()=a×()a÷()=a×()
课外练习
1、计算
(1)2.5×4.4
(2)3.6×9.2-2×0.36
(3)222×4.4+8.9×888
(4)6.3÷2.5÷0.7×0.5 2、0.1÷(0.1÷0.2)÷(0.2÷0.3)÷(0.3÷0.4)÷…÷(9.9÷10)