AMC8 1991

AMC8 1991 · Q16

AMC8 1991 · Q16. It mainly tests Transformations, Logic puzzles.

The 16 squares on a piece of paper are numbered as shown in the diagram. While lying on a table, the paper is folded in half four times in the following sequence: (1) fold the top half over the bottom half (2) fold the bottom half over the top half (3) fold the right half over the left half (4) fold the left half over the right half Which number square is on top after step 4?

纸上有一个由16个方格组成的图示编号。当纸平放在桌子上时，按照以下顺序对折四次：(1) 将上半部分折叠到下半部分 (2) 将下半部分折叠到上半部分 (3) 将右半部分折叠到左半部分 (4) 将左半部分折叠到右半部分第4步后，哪个编号的方格在最上面？

(A) 1 1

(B) 9 9

(D) 14 14

(E) 16 16

Answer

Correct choice: (B)

正确答案：（B）

Solution

A fold from the top leaves #9-16 on the bottom. A fold from the bottom leaves #9-12 on the bottom. A fold from the right leaves #9 and #10 on the bottom. A fold from left leaves #10 on the bottom with number #9 moving to the top.

从顶部折叠后，#9-16在底部。从底部折叠后，#9-12在底部。从右侧折叠后，#9和#10在底部。从左侧折叠后，#10在底部，编号#9移到顶部。

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