用简便方法计算下面各题.(1)( 1 5 + 2 7 )×5×7(2)999 8 9 +9

2024-12-03 20:26:48
推荐回答(1个)
回答1:

(1)(
1
5
+
2
7
)×5×7
=
1
5
×5×7+
2
7
×5×7,
=7+10,
=17;

(2)999
8
9
+99
8
9
+9
8
9
+
1
3

=(1000-
1
9
)+(100-
1
9
)+(10-
1
9
)+
1
3

=(1000+100+10)-
1
9
×3+
1
3

=1110-(
1
3
-
1
3
),
=1110;

(3) 444
4
5
×1.25

=(444+
4
5
)×
5
4

=444×
5
4
+
4
5
×
5
4

=555+1,
=556;

(4)231÷ 231
231
232

=231÷
232×231+231
232

=231×
232
(232+1)×231

=
232
233