题目内容

计算下面各题,能用简便方法计算的要用简便方法计算.
8
9
×[
3
7
÷(
2
3
+
1
7
)]
(873×477-198)÷(476×874+199)
199.9×19.98-199.8×19.97
4
5
×
12
13
+16×
1
5
+
1
5
×
4
13
(1)
8
9
×[
3
7
÷(
2
3
+
1
7
)],
=
8
9
×[
3
7
÷
17
21
],
=
8
9
×
9
17

=
8
17


(2)(873×477-198)÷(476×874+199),
=[873×(476+1)-198]÷[476×(873+1)+199],
=[873×476+873-198]÷[476×873+476+199],
=[873×476+675]÷[476×873+675],
=1;

(3)199.9×19.98-199.8×19.97,
=199.9×19.98-19.98×199.7,
=(199.9-199.7)×19.98,
=0.2×19.98,
=3.996;

(4)
4
5
×
12
13
+16×
1
5
+
1
5
×
4
13

=
1
5
×
48
13
+16×
1
5
+
1
5
×
4
13

=(
48
13
+
4
13
+16)×
1
5

=(4+16)×
1
5

=20×
1
5

=4.
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