直接写出得数．= = = == = = =
用你喜欢的方法计算 （+）÷+13÷（+）×31×19.97+199.7×6.8+199.7×0.1 （1﹣+）÷0.252﹣÷﹣÷﹣÷6．
下面各题怎样简便怎样算． +++﹣﹣ ﹣+2﹣．
12﹣（+）×24．
计算下面各题．×45+÷﹣×（+）÷．
怎样简便怎样算．×16×÷12÷÷[（﹣）×24]×+÷++×÷（+）
= 
= 
= 
=
= 
= 
= 
=
+
）÷
+
13÷（
+
）×
31×19.97+199.7×6.8+199.7×0.1
+
）÷0.252﹣
÷
﹣
÷
﹣
÷6．
+
+
+
﹣
﹣
﹣
+
2﹣
．
+
）×24．
×45+
÷
﹣
×
（
+
）÷
．
×16×
÷12÷
÷[（
﹣
）×24]
×
+
÷
+
+
×
÷（
+
）
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