MHB How can you solve the eight-digit challenge?

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The eight-digit challenge requires placing the digits 1 through 8 in a grid while ensuring that no two consecutive digits are adjacent in any direction. Participants discuss various strategies for solving the puzzle, emphasizing the importance of planning placements to avoid conflicts. Some suggest starting with the highest or lowest digits to create a foundation for the arrangement. Others explore different configurations and patterns to achieve a valid solution. The challenge encourages logical reasoning and creative problem-solving skills.
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Place the digits 1 through 8 in the boxes
so that no two consecutive digits are adjacent
(not vertically, horizontally or diagonally).
. . \begin{array}{cccccccccc}&& * & - & * & - & * \\ && | && | && | \\ * &-& * &-& * &-& * &-& * \\ | && | && | && | && | \\ * &-& * &-& * &-& * &-& * \\ && | && | && | \\ && * & - & * & - & * \end{array}
 
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The two central boxes are adjacent to the most other boxes, so it makes sense to put 1 and 8 in them to maximize our options (since 0 and 9 are not valid digits). By horizontal symmetry, it doesn't really matter what order we put them in. So we start with:​

Code:
  ? ?
? 1 8 ?
  ? ?

Here we automatically deduce that 7 must go in the leftmost box and 2 in the rightmost box, otherwise there would be two adjacent consecutive numbers. Hence:

Code:
  ? ?
7 1 8 2
  ? ?

Hence we have 3, 4, 5, and 6 left to place. We see that 6 must be in one of two boxes on the right, and 3 must be in one of the boxes on the left. Furthermore, 4 and 5 cannot be put adjacent to one another. This forces the following configuration (up to symmetry):

Code:
  3 5
7 1 8 2
  4 6

And the puzzle is solved.
 
Here is a little puzzle from the book 100 Geometric Games by Pierre Berloquin. The side of a small square is one meter long and the side of a larger square one and a half meters long. One vertex of the large square is at the center of the small square. The side of the large square cuts two sides of the small square into one- third parts and two-thirds parts. What is the area where the squares overlap?

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