脱式计算(能简算的要简算) 2.5×1.2+0.25×281.9+19.9+199.9+0.3.
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解:(1)2.5×1.2+0.25×28,
=0.25×12+0.25×28,
=0.25×(12+28),
=0.25×40,
=10;
(2)1.9+19.9+199.9+0.3,
=1.9+19.9+199.9+0.1+0.1+0.1+0.1,
=(1.9+0.1)+(19.1+0.1)+(199.9+0.1),
=2+20+200,
=222.
解析分析:(1)把2.5×1.2化成0.25×12,进行简算.(2)运用加法的运算定律进行简算.
点评:考查了小数运算定律的灵活运用.