下面各題,怎樣簡便就怎樣算1),下面各題,怎樣簡便就怎樣算 (1)2 15 8 73 1 27 7 85 (2)11 87 (8 2 1 87) (3)5

2021-03-17 01:16:13 字數 1827 閱讀 9101

1樓:█花仔

解:(1)2.15+8.73+1.27+7.85=(2.15+7.85)+(8.73+1.27),=10+10,

=20;

(2)11.87-(8.2+1.87),

=11.87-1.87-8.2,

=10-8.2,

=1.8;

(3)5.42-3.87-1.13,

=5.42-5,

=0.42;

(4)4.38-1.56+0.62-0.44,=(4.38+0.62)-(1.56+0.44),=5-2,

=3; (5)0.4×270×2.5,

=(0.4×2.5)×270,

=270;

(6)(40+1.25)×8,

=40×8+1.25×8,

=320+10,

=330;

(7)(12.5-0.05)×8,

=12.5×8-0.05×8,

=100-0.4,

=99.6;

(8)2.6×8.5+8.5×7.4,

=(2.6+7.4)×8.5,

=85;

(9)9.9×6.9-6.9×3.9,

=(9.9-3.9)×6.9,

=6×6.9,

=41.4;

(10)5.6×99+5.6,

=5.6×(99+1),

=560;

(11)2.5×(1.9+1.9+1.9+1.9),=2.5×4×1.9,

=10×1.9,

=19;

(12)7.2÷1.25÷8,

=7.2÷8÷1.25,

=0.9÷1.25,

=0.72.

下面各題,怎樣簡便就怎樣算. (1)2.15+8.73+1.27+7.85 (2)11.87-(8.2+1.87) (3)5.42-3.87-

2樓:悠悠hanp慎

(1)2.15+8.73+1.27+7.85=(2.15+7.85)+(8.73+1.27),=10+10,

=20;

(2)11.87-(8.2+1.87),

=11.87-1.87-8.2,

=10-8.2,

=1.8;

(3)5.42-3.87-1.13,

=5.42-5,

=0.42;

(4)4.38-1.56+0.62-0.44,=(4.38+0.62)-(1.56+0.44),=5-2,

=3; (5)0.4×270×2.5,

=(0.4×2.5)×270,

=270;

(6)(40+1.25)×8,

=40×8+1.25×8,

=320+10,

=330;

(7)(12.5-0.05)×8,

=12.5×8-0.05×8,

=100-0.4,

=99.6;

(8)2.6×8.5+8.5×7.4,

=(2.6+7.4)×8.5,

=85;

(9)9.9×6.9-6.9×3.9,

=(9.9-3.9)×6.9,

=6×6.9,

=41.4;

(10)5.6×99+5.6,

=5.6×(99+1),

=560;

(11)2.5×(1.9+1.9+1.9+1.9),=2.5×4×1.9,

=10×1.9,

=19;

(12)7.2÷1.25÷8,

=7.2÷8÷1.25,

=0.9÷1.25,

=0.72.

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