问题
解答题
能简算的用简便方法计算．
[2.5-（
|
答案
①
÷（4 9
-0.2）5 6
=
÷（4 9
-5 6
）1 5
=
÷4 9 19 30
=
；40 57
②
×（7.2+19 25
）-4 5
÷17 25 1 8
=
×（19 25
+36 5
）-4 5
÷17 25 1 8
=
×8-19 25
÷17 25 1 8
=
×8-19 25
×817 25
=（
-19 25
）×817 25
=
×82 25
=
；16 25
③[2.5-（
+0.15）÷0.6]×17 20 2 5
=[2.5-（0.85+0.15）÷0.6]×0.4
=[2.5-1÷0.6]×0.4
=（2.5-
）×0.45 3
=2.5×0.4-
×0.45 3
=1-2 3
=
；1 3
④（
+5 8
）×8+1 27 19 27
=
×8+5 8
×8+1 27 19 27
=5+
+8 27 19 27
=5+（
+8 27
）19 27
=5+1
=6．