II.7 Rearrangement of 12 cards

Twelve cards in which the numbers from 1 to 12 were written are put in order like #1 in a figure at first.

In accordance with the same rule, it rearranges with #2, #3, #4, and .... after that.

Answer each of following questions.

(1) Fill in the blank of #5 in a figure.

(2) Find the number which is to be the same as #1 for the first time after #2.

(3) Fill in the blank of #2006 in a figure.






















Answer
(1) 

(2) #11 
(3) 

Solution
(1) The rule of rearrangement of the cards should be confirmed.

According to #1 and #2, 1~6 in the left column rearranged every other one and 7~12 in the right column is put between them.

Thinking it more briefly, as shown in a figure, 7~12 are put among 1~6 of a left column and all of them are rearranged.

Based on this rule, #5 is come out by rearranging #4.

(2) It would be better to rearrange in order by yourself until it comes to be the same as #1.

It is #11 to become the same as #1 as shown in a figure.



(3) According to (2), since #1, #11, #21, and #31 comes to be the same, it turns out that the cycle which comes to be the same is 10. 

Therefore, 2006 / 10 = 200 remainder 6. 

This outcome means that #2006 comes to be the same as #6.