用简便方法计算．①45×9.9；②4.82×88+48.2×1.2；③4.2×102﹣8.4；④7.86﹣（5.63﹣0.86）﹣1.37．
计算下面各题（写出主要的计算过程）．
直接写出得数：+=﹣=+=+= 1﹣=﹣=+=﹣=++=+﹣=
直接写出得数．+=﹣=+=﹣=+= 1﹣=﹣=+=
脱式运算，能简便的要用简便方法计算．﹣++++ 1﹣﹣．
直接写出的数+=﹣=+ 880÷8= 19×5= 36÷3÷2= 5×5+4= 50﹣24÷4= 300×30= 88+112=
+
=
﹣
=
+
=
+
= 1﹣
=
﹣
=
+
=
﹣
=
+
+
=
+
﹣
=
+
=
﹣
=
+
=
﹣
=
= 1﹣
=
﹣
=
+
=
﹣
+
+
+
1﹣
﹣
．
+
=
﹣
=
+
880÷8= 19×5=
粤公网安备 44130202000953号