问题 解答题
用简便方法计算(要求写出主要简算过程).
1
6
+
2
9
+
5
6
+
5
9

15.6÷
4
9
+4
2
5
×2.25
答案

(1)

1
6
+
2
9
+
5
6
+
5
9

=(

1
6
+
5
6
)+(
5
9
+
2
9
),

=1+

7
9

=1

7
9

(2)15.6÷

4
9
+4
2
5
×2.25,

=15.6×

9
4
+4.4×2.25,

=15.6×2.25+4.4×2.25,

=(15.6+4.4)×2.25,

=20×2.25,

=45.

判断题
问答题 简答题