1 用简便方法计算下面各题。 、
2 9
-
7 16
×
2 9
=(1-176 )×
2 9
=
1 8
196×
21 91
2 ×4 41
=
6 5
=
1 8
用简便方法计算下面各题。
1 × 1+ 1 × 2 15 3
1 2
=
1 2
×(
115+
1 3
)
=
1
1 2
×
63 15
=
1 5
4 5
×
79×
5 8
=
14 × 15
5 8
1
×
2
7 9
=
7 18
用简便方法计算下面各题。
5 6
×
59+
5 9
×
1 6
=
5 9
×(
5 6
+
1 6
)
=
5 9
×1
=
5 9
5 7
×16×
21 5
=
15 17
×2513×1 16
=3×16
=48
第10面
计算下面各题。
1 3
×
3 5
+1
=
1 13
×
351+1
=
1 5
+1
=1 1
5
5 7
-
5 9
×
5 7
=(1-
5 9
)×
5 7
=
4 9
×
5 7
=
20 63
1-
5 7
×
21 25
1
=
1-