范文一:五年级小数乘法简算
第二讲 小数的简算——乘法
复习小结:
(1)运算定律: 交换律:a ×b=b×a
乘法结合律:a ×b ×c= a×(b×c) 乘法分配律:a ×(b+c)= a×b+ a×c
(2)乘法里,哪些数相乘的积是整十、整百、整千数?
5×2=10、25×2=50、25×4=100、50×4=200、50×2=100、125×4=500、125×8=1000、500×2=1000
(3)用简便方法计算:5×73×4 125×16 32×403
前面我们复习了整数乘法的有关运算定律,灵活运用这些定律,可以使一些整数乘法的计算简便.整数乘法里的这些运算定律,在小数乘法中适用吗?如果适用,该怎样用呢?这就是这讲我们要探讨的问题──小数乘法的简便计算 例题讲解:
0.25×4.48×4 =0.25×4×4.48 =4.48
跟踪练习:1.25×6.3×8 0.8×(4.3×1.25)
1.25×8.88 =1.25×(8×1.11) =(1.25×8)×1.11 =1.1
跟踪练习:2.5×4.44 12.5×1.6
0.65×201 =0.65×(200+1) =0.65×200+0.65×1 =130+0.65 =130.65
跟踪练习:4.82×101 2.35×199
0.85×198 2.4
12.5×64×2.5×0.5
=12.5×(8×4×2)×2.5×0.5 =12.5×8×4×2×2.5×0.5
=(12.5×8)×(4×2.5)×(2×0.5)=100×10×1 =1000
跟踪练习:2.5×1.25×3.2 1.25
1.8×36+1.8×64 =1.8×(36+64) =1.8×100 =180
跟踪练习:2.4×0.6+2.4×0.4 1.25×102 ×0.5×4.8 ×7.7+1.25×0.3
7.6×0.8+0.2×7.6 12.9×15―11.9×15
3.12×99+3.12 =3.12×99+3.12×1 =3.12×(99+1) =3.12×100 =312
跟踪练习: 28.6×101-28.6 32.4+99×32.4
3.58×99+3.58 9.13×201-9.13
以上例题各自都用了哪些运算定律?请同学们仔细观察 综合测评:
100.5×7.5 2.5×4×7.5
(0.8×0.5)×0.4 (2.5-0.25)×0.4
0.25×0.73×4 1.25×16
0.86×15.7-0.86×14.7 3.12+3.12×99
0.125×0.25×0.5×64 9.16×1.5-0.5×9.16
4.85×3.6-3.6+6.15×3.6 7.6×8.5+7.6×125 +7.6×0.1
趣味数学:
把下题中的“☆”换成适当的数字,并确定原式中第一个因数小数点的位置
。
第三讲 小数的简算——乘法
例题讲解: 注意观察,“凑”出相同因数,再把相同因数提出来,不同因数关起来。 2.3×86+770×0.86 =230×0.86+770×0.86 =(230+770)×0.86 =1000×0.86 =860
跟踪练习:27×4.3+57×2.7
26.39×36+2.639×830-263.9×1.9
9.99×0.7+1.11×2.7 =9.99×0.7+9.99×0.3 =9.99×(0.7+0.3) =9.99×1 =9.99
跟踪练习:99.99×1.1+11.11×0.1 75
7.5×8.88+2.22×7.5+2.5×11.1 20.05
333387.5×89+890×66661.25 3.72×3.5+62. 8×0.35 ×4.7+15.9×25 ×39+200.5×4.1+40×10.025
从例题中你用到了哪些学过的知识?
综合测评:
6.28×3.7+6.28×7.3-6.28 0.888×125×73+999×3.
0.78×78+7.8×2.2 6.4
46×0.33+54×0.33
0.6×2.57+6×74.3
17.48×37+17.48×82-174.8×1.9
383.75×7.9+79×61.625 2005
×3.28+4.6×3.28-3.28 7.09×10.8-0.8×7.09 172.4×6.2+2724×0.38 19.98×37-199.8×1.9+1998×0.82×18-200.5×80+20050×0.1
6.81+6.81×99 46×0.33+54×0.33
11×22+0.22×3300+660×2.2 15.6×13.1-15.6-15.6×2.1
3.74×2.85+8.15×3.74-3.74 (0.125+1.25+12.5+125)×8
2.89×4.68+4.68×6.11+4.68 3.6×4.8+3.6×4.2+3.6
28.67×67+32×28.67+573.4×0.05 15.6×13.1-15.6-15.6×2.1
6.25×0.16+264×0.0625+5.2×6.25+0.625×20
趣味数学:
(1+0.23+0.34)×(0.23+0.34+0.65)-(1+0.23+0.34+0.65)×(0.23+0.34)
范文二:五年级上册小数简算
1) 4.8+8.63+5.2+0.37
2) 5.93+0.19+2.81 3) 1.76+0.195+3.24 4) 2.35+1.713+0.287+7.65 5) 1.57+0.245+7.43 6) 6.02+3.6+1.98 7) 0.134+2.66+0.866
8) 1.27+3.9+0.73+16.1
9) 3.07-0.38-1.62
10) 8-2.45-1.55
11) 23.4-0.8-13.4-7.2
12) 0.32×403
13) 0.25×36
14) 12.7-(3.7+0.84)
15) 36.54-1.76-4.54
16) 7.6×0.8+0.2×7.6 17) 0.85×199 18) 0.25×8.5×4 19) 1.28×8.6+0.72×8.6 20) 12.5×0.96×0.8 21) 10.4-9.6×0.35
22) 0.8×(4.3×1.25)
23) 3.12+3.12×99
24) 28.6×101-28.6
25) (4.23+6.17)×0.8
26) 0.86×15.7-0.86×14.7
27) 2.4×102
28) 14-7.32-2.68
29) 2.64+8.67+7.36+11.33
30) 2.31×1.2×0.5 31) (2.5-0.25)×0.4 32) 9.16×1.5-0.5×9.16 33) 3.6-3.6×0.5 34) 4.5÷1.8 35) 4.2÷3.5
36) 930÷0.6÷5
37) 63.4÷2.5÷0.4
38) 4.9÷1.4
39) 3.9÷(1.3×5)
40) (7.7+1.54)÷0.7
41) 2.5×2.4
42) 2.7÷45
43) 0.35×1.25×2×0.8
44) 32.4×0.9+0.1×32.4
45) 15÷0.25
46) 70÷28 15÷(0.15×0.4)
47) 4.25÷2.5×9.9+0.17
范文三:五年级 小数乘法简算
1.25x32x2.5 3.2 ×0.6+2.8×0.6
0.39x199 3.65x10.1
12.9x99+12.9 7.09x10.8-0.8x7.09
5.4x11-5.4 0.65x101
2.5x26+2.5x68 0.25×
( 1.25-0.125)×8 3.6×
3.72×3.5+6.28×3.5 15.6×
4.8×7.8+78×0.52 4.8×
16.2×4 102 13.1-15.6-15.6×2.1 100.1
56.5×99+56.5 7.09×10.8-0.8×7.09
0.85x9.9 0.25X36
706X0.8+0.2X7.6 12.5X0.96X0.8
10.4-9.6X0.35 2.31X1.2X0.5
2.4X102 28.6X101-28.6
36.54-1.76-4.54 (2.5-0.25)X0.4
9.16X1.5-0.5X9.16 3.6-3.6X0.5
范文四:五年级小数简算练习题
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五年级小数简算练习题
3.72×3.5,6.28×3.536.8,3.9,6.1.48,
4.8×7.8,78×0.5.6×102
32,4.9,0.94.8,4.8×0.5
4.8×100.156.5×9.9,56.5
4.02,5.4,0.9.17,1.8,3.2
3.68,7.56,2.68.85,2.34,0.85,4.66
3.82,2.9,0.18,9.1.6,4.8,3.6
5.27,2.86,0.66,1.13.35,4.68,2.65
0.398+0.36+3.6415.75+3.59,0.59+14.25
6.4×0.25,3.6? ×.09×10.8,0.8×7.0,5.6,1.8,15.6,7.2.14,0.53,2.447.8,7.45+8.2.5,13.75
4.2?3.5320?1.25? 18.76×9.9,18.76
3.52?2.5?0.44.78?0.2,3.443.9,4.1,6.1,5.9
0.49?1.4
3.65×10.1
5.6?3.5
0.89×100.1
5.83×2,4.27
4.36×12.5×8
27.5×3.7,7.5×3.7
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1.25×2.5×323.6,0.6×2.6,3.6×0.
15.2?0.25?9.6?0.8?0.4.2×99,4.146.5,17.8? ?8?0.129.7×99,9.15.6×13.1,15.6,15.6×2.10.65×101 .54?2.5?0.43.83×4.56,
3.83×5.44
6048,975-304498×39
6048,75-3005
6098,935-1045
1048,975-345
878×29
9948,275-304
68,975-345
648×75-3005
404×24,758
640×75?35
68×975-345
5690×6?35
68,975?345
648,75-385,975-345
68,975-345
48×975-304
6048,975-3045
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20.5-1.074-8.35×5.5
48×975-3045
20.5-1.074-8.35×5.5
548×975-3045
6748,975-5045
0.425×0,38?0,01
748,95-45
0.425×0,38?0,01
52.8?0.75×0.25
45× ?23
327,9664?32×25
586-45×81?27
3.68?4.6,6.32
604×24,758
604×24,758
478×378×39
478×19
727,9660?30×25
58-45×80?25
368?46,632
644×14,8508×59
0.25×8.5×40.25×0.73×0.25×16.2×4
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0.25×36
---------------------------------------------------
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×812.5×0.96×0.8.36×12.5×8
1.25×2.5×3.2×0.25×12.5
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4.8×10.1 .6×1020.39×199
0.32×40.65×10.1 0.85×9.9
0.25×0.280.25×4?0.25×4.29×0.25×4
0.125×8.8
] [60-
2.881?0.43-0.24×3.5
28-
777×9+1111×3
36×10.12.2×4+17.8×?12.15.6?16× ]?0.120×[?0
.4+0.15]2.55×7.1+2.45×7.1 0.8×[15.5-]
?31.5×4?
0.64×25×7.8+2.?2.5+2.5?2
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36.25?4.25×9.9180,705×6
24?2.4,2.5×0.8
671×15-974
5.67×0.2-0.62
0.78+5.436+1
10.?4x8?9-1?3
20.x2?9+1?3
7.2?0.8-1.2×5
2.55×7.1+2.45×7.1
?69×12+1419.4×6.1×2.18.1×0.92+3.930.4×0.7×0.
2.×?4+1?.x5?6+5?
14.1x5?6-5?16.?9x18-14x2?5.5?6. 178-145?5×6+46.5×8-77×9+1111×?5
31.5×4?0.64×25×7.8+2.?2.5+2.5?2
194,64.8?1.8×0.6.72?4.25×9.9180,705×6
24?2.4,2.5×0.?7671×15-974
469×12+1492
5.67×0.2-0.62
0.4×0.7×0.250.78+5.436+1
240×78?
2160?〔×18〕 80
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85×
81432?[37.85-
,76×64
405× 19.4×6.1×2. 18.1×0.92+3.0.043×24+0.87.07×0.86+9.11437×27,
27×56〔75-〕?15,840?24×5325?13×8870?1437×27
,27×563] ×306× [192,]×67
81432? ,76×60,?0.18
2.881?0.43,0.24×3.50.8×〔15.5-〕 ?5
194,64.8?1.8×0.936.72?4.25×9..416?
0.8×[?1.2] ?8. 0.12×.8?0.12×4.8
?12-700? 156×[?3]
?1.685+14× 120-36×4?18+35
9.72×1.6-18.305?.2×?1.?
?8.50.12×.8?0.12×4.8?1.6
120-36×4?18+315-10.75×0.4-5.47+45×2-4160?52
?[×0.9-1.15] ?2.5
?1.65.4?[2.6×+0.62]
12×6?-.2×6+?1.?1. 120-144?18+347+45×2-4160?5 ? 5?
812-700? 120-36×4?18+35
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?8.50.12×.8?0.12×4. 0.8×〔15.5-〕 ?1.5×4? 0.64×25×7.8+2.?2.5+2.5?2
194,64.8?1.8×0.6.72?4.25×9.180,705×6
24?2.4,2.5×0. ?7
671×15-974
46
9×12+1492
405×
0.8×[?1.2] 19.4×6.1×2.67×0.2-0.618.1×0.92+3.924+0.875×90.
4×0.7×0.20.75×10 100-56.23
31.50,160?40
?.120-144?18+33.347+45×2-4160?52?.95?.178-145?5×6+420+580-64×21?28
37.812-700?
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范文五:五年级奥数小数除法简算专题
五年级奥数小数除法简算专题
练习题
*1、用简便方法计算下面各题.
(1)1.8÷0.5
(3)2.1÷2.5
(5)1.2÷0.125
(7)0.78÷0.25÷4
(9)9.6÷(9.6×4) (11)5.6÷0.8÷0.2 (13) 9.9856÷125÷8 (15) 29.7÷(0.9×0.3) (17) 785.1÷8÷12.5 (2)7.3÷0.5
(4)1.3÷0.25 (12) 370÷12.5÷0.08
(6)21÷1.25 (14) 7.38÷5÷2
(8)3.4÷1.25÷8 (16) 5.88÷(0.6×0.7)
(10)3.14÷(3.14×8) (18)27.8÷2.5÷4
**2
、已知,则A —B 与A ÷B 的结果各是多少?
**3、一个小数,若把小数点向右移动一位,则所得到的数比原数大了42.84,原数是多少?
**4、已知A ×0.99=B×4/5=C×9/10=D×0.909=E÷50/49=F÷100/99,请把A 、B 、C 、D 、E 、F 从小到大排列起来。
***5、有23个自然数,让小红计算它们的平均数,使结果保留三位小数,小红计算的答案 是16.654。老师说最后一位数字错了,其他的数字都对,正确的答案应该是多少?
6. 给小数0.7082169453添上表示循环节的两个点, 使其变成循环小数.
(1)如果把两个点加在8和3上面,那么,第100位的数应该是几?