一堆圆木,最上层有9根,最下层有29根,而且每相邻两层都相差2根.这堆圆木一共有多少根?
2023-04-27
问题描述:
一堆圆木,最上层有9根,最下层有29根,而且每相邻两层都相差2根.这堆圆木一共有多少根?最佳答案:
层数:
(29-9)÷2+1
=20÷2+1
=10+1
=11(层),
(9+29)×11÷2
=38×11÷2
=418÷2
=209(根),
答:这堆圆木一共有209根.
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2023-04-27
问题描述:
一堆圆木,最上层有9根,最下层有29根,而且每相邻两层都相差2根.这堆圆木一共有多少根?最佳答案:
层数:
(29-9)÷2+1
=20÷2+1
=10+1
=11(层),
(9+29)×11÷2
=38×11÷2
=418÷2
=209(根),
答:这堆圆木一共有209根.
热门标签