计算下面各题,能用简便算法的用简便算法0.25×1.2+2.8×0.25 0.65×101 67.8-7.8×4.9 3
1个回答

(1)0.25×1.2+2.8×0.25,

=0.25×(1.2+2.8),

=0.25×4,

=1;

(2)0.65×101,

=0.65×(100+1),

=0.65×100+0.65×1,

=65+0.65,

=65.65;

(3)67.8-7.8×4.9,

=67.8-38.22,

=29.58;

(4)3.2×1.25×2.5,

=(0.8×1.25)×(4×2.5),

=1×10,

=10;

(5)0.8×(2.5×0.125),

=2.5×(0.8×0.125),

=2.5×0.1,

=0.25;

(6)16.8÷40÷0.25,

=16.8÷(40×0.25),

=16.8÷10,

=1.68.