用简便方法计算．（1）1.5×105（2）2.33×0.5×4（3）24.6+18.7+15.4（4）1.2×2.5+0.8×2.5．
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直接写出得数．== 1﹣=+0.625=== 3﹣=+0.75=
口算：+= 1.52=﹣= 1.8÷2.7=﹣=+= 4+= 3﹣=﹣=﹣=﹣﹣=++=
（1）+= （2）﹣= ．
直接写出得数．========
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= 1﹣
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+0.625=
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= 3﹣
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+0.75=
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= 1.8÷2.7=
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= 4+
= 3﹣
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﹣
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﹣
= ．
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