计算下列各题,能简便的要简便计算. 618÷45+1620 11/8÷(1/4+2.5×4/5) 6/7-6/7×(2/3+1/9) 2008÷20082008/2009. 200.8×73-6.3×2008 99-97+95-93+91-

问题描述:

计算下列各题,能简便的要简便计算.
618÷45+1620

1
1
8
÷(
1
4
+2.5×
4
5
6
7
-
6
7
×(
2
3
+
1
9
2008÷2008
2008
2009
200.8×73-6.3×2008 99-97+95-93+91-89+…+7-5+3-1.

(1)618÷45+1620,
=13

11
15
+1620,
=1633
11
15

(2)1
1
8
÷(
1
4
+2.5×
4
5
),
=1
1
8
÷(
1
4
+2),
=1
1
8
÷
9
4

=
9
8
×
4
9

=
1
2

(3)
6
7
-
6
7
×(
2
3
+
1
9
),
=
6
7
×(1-
2
3
-
1
9
),
=
6
7
×
2
9

=
4
21

(4)2008÷2008
2008
2009

=2008÷
2008×2009+2008
2009

=2008÷
2008×2010
2009

=2008×
2009
2008×2010

=
2009
2010

(5)200.8×73-6.3×2008,
=2008×7.3-6.3×2008,
=2008×(7.3-6.3),
=2008×1,
=2008;
(6)99-97+95-93+91-89+…+7-5+3-1,
=(99-97)+(95-93)+(91-89)+…+(7-5)+(3-1),
=2+2+2+2+…+2+2(25个2),
=2×25,
=50.