问题 解答题
神机妙算细又巧!
7
11
×
8
9
+
7
11
÷
9
10
 ②1375+450÷18×25
③4×0.8×2.5×12.5④7.8-2.3-2.7
⑤(
7
9
+
4
21
-
3
7
)×6.3⑥0.9×(99+0.9)
答案

7
11
×
8
9
+
7
11
÷
9
10

=

7
11
×
8
9
+
7
11
×
10
9

=

7
11
×(
8
9
+
10
9
),

=

7
11
×2,

=

14
11

②1375+450÷18×25,

=1375+625,

=2000;

③4×0.8×2.5×12.5,

=4×2.5×(12.5×0.8),

=10×10,

=100;

④7.8-2.3-2.7,

=7.8-(2.3+2.7),

=7.8-5,

=2.8;

⑤(

7
9
+
4
21
-
3
7
)×6.3,

=

7
9
×6.3+
4
21
×6.3-
3
7
×6.3,

=4.9+1.2-2.7,

=3.4;

⑥0.9×(99+0.9),

=0.9×(100-1+0.9),

=0.9×(100-0.1),

=0.9×100-0.1×0.9,

=90-0.09,

=89.91.

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