用简便方法计算145×59+59×315(59-418)×3649×49502829×30.-数学

题文

用简便方法计算
14
5
×
5
9
+
5
9
×
31
5

(
5
9
-
4
18
)×3649×
49
50

28
29
×30.
题型:解答题  难度:中档

答案


(1)
14
5
×
5
9
+
5
9
×
31
5

=(
14
5
+
31
5
)×
5
9

=9×
5
9

=5;

(2)(
5
9
-
4
18
)×36,
=
5
9
×36-
4
18
×36,
=20-8,
=12;

(3)49×
49
50

=(50-1)×
49
50

=50×
49
50
-1×
49
50

=49-
49
50

=48
1
50


(4)
28
29
×30,
=
28
29
×(29+1),
=