一堆规格相同的水泥管，呈梯形堆放（如图），这堆水泥管共有多少根？
1﹣= ．
1+3= ．
= ．
口算 55+37= 80﹣26= 1400﹣800= 2+210= 9+300= 82+0= 1﹣= += ﹣= ．
口算我最棒.+=+=﹣=﹣=+= 1+=﹣0.2=+0.3=+= 1﹣+=﹣﹣=++=
= ．
+3= ．
= ．
= 
+
= 
﹣
= ．
+
=
+
=
﹣
﹣
=
+
= 1+
=
﹣0.2=
+0.3=
+
= 1﹣
+
=
﹣
﹣
=
+
+
=
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