| 计算。(能简算的要简算) | ||||
|
| (1)2 .58 ×1 .9 =2.58×(2-0.1) =2.58×2-2.58×0.1 =5.16-0.258 =4.902 |
(2)10 .8 ÷1 .2 =10.8÷(0.2×6) =10.8÷0.2÷6 =54÷6 =9 |
| (3)4 .5 ÷0 .5 ÷9 =4.5÷(0.5×9) =4.5÷4.5 =1 |
(4)0 .32 ×1 .25 ×0 .25 =(0.4×0.8)×1.25×0.25 =(0.8×1.25)×(0.4×0.25) =1×0.1 =0.1 |
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○8.677(3)5.4 × 0. 9 ○0.9 × 5.4 (4)0. 728÷ 0.9○0.728(5)
○
(6) 2.5 ×2 ×0.2○2.5 ×0.2 ×2(7)2.5 ×3 ×4○0.5 ×6 ×10 (8)1.3○1.3334(9)1.2 +1.2 +1.2 ○1.2 ×1.2×1.2(10)4(2.5 + a )○4 ×2.5 +4 a(11)5.6÷0.5○5.6×2(12)3. 69 × 0.17○3. 69 +0.17
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a.20[ ]
a.3[ ]
[ ]
a.24.3×3[ ]
a.1.2