计算：①15.6789÷20÷5= ②34.5×8.23﹣34.5+2.77×34.5= ③0.9999×0.7+0.1111×2.7= ．
口算．+=﹣= 4.3﹣1.6=+= 1﹣=﹣= 2﹣=+=
直接写得数．﹣=﹣= 2+= 3﹣=+=﹣=+=﹣=
直接写出得数．+=﹣=+=﹣=﹣= 1﹣= 0.2+= 1.2÷5=
直接写出得数.+= ；+= ；﹣0.125= ；﹣= ；+0.3= ； 10﹣= ；+= ；﹣= ．
计算下面各题．+=﹣=+=﹣=﹣+=﹣（+）=+﹣=
+
=
﹣
= 4.3﹣1.6=
+
=
=
﹣
=
+
=
﹣
=
= 2+
= 3﹣
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+
=
﹣
=
+
=
﹣
=
+
=
﹣
=
+
=
﹣
=
﹣
= 1﹣
= 0.2+
= 1.2÷5=
+
= ；
+
= ；
﹣0.125= ；
﹣
= ；
+0.3= ； 10﹣
= ；
+
﹣
+
=
﹣
=
+
=
﹣
=
+
=
+
）=
+
﹣
=
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