问题 解答题
用简便方法计算.
18
25
×99+
18
25
12.9×97+12.9×4-12.9
3
4
×
9
10
+
1
4
÷1
1
9
答案

(1)

18
25
×99+
18
25

=

18
25
×(99+1),

=

18
25
×100,

=72;

(2)12.9×97+12.9×4-12.9,

=12.9×(97+4-1),

=12.9×100,

=1290;

(3)

3
4
×
9
10
+
1
4
÷1
1
9

=(

3
4
+
1
4
)×
9
10

=1×

9
10

=

9
10

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