问题 解答题
简算:
1.2×2.5

3.14×78+31.4×2.2.
答案

(1)1.2×2.5,

=0.3×(4×2.5),

=0.3×10,

=3;

(2)3.14×78+31.4×2.2,

=3.14×78+3.14×22,

=3.14×(78+22),

=3.14×100,

=314.

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