问题标题:
用简便方法计算1.2×2.5+2.8×2.54.8×2.5.
问题描述:

用简便方法计算

1.2×2.5+2.8×2.54.8×2.5.

苏占东回答:
  (1)1.2×2.5+2.8×2.5,   =(1.2+2.8)×2.5,   =4×2.5,   =10;   (2)4.8×2.5,   =(4×1.2)×2.5,   =(4×2.5)×1.2,   =10×1.2,   =12.
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