Consider the palindromic phrase
In how many ways can be read if you start at any and are restricted to read only up, down, left or right to adjacent letters?
Note: You are allowed to use the same letter twice, and you each case is counted twice since you can read a case from one direction, but it can also be read from the opposite direction.
You may use a calculator for the final step
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We will first count all SANITARYZOO we can make. If we focus on each quarter of the diamond grid, we find that there is 1 way to choose the S , after which there are two choices for each letter i.e. there are 2 ways to choose an A , after which there are two ways of choosing an N and so forth. Since there are 11 letters in SANITARYZOO , there are 2 1 0 of these in each quarter. Thus, there are 4 × 2 1 0 altogether. However, we have over-counted when the words lie along the vertical or horizontal diagonals. Thus, there are actually 4 × 2 1 0 − 4 words. Since each of these words can be paired with any other (including itself) to create OOZYRATINASANITARYZOO , there are ( 4 × 2 1 0 − 4 ) 2 = 1 0 2 0 2 = 1 6 7 4 4 4 7 4 total words.
Therefore, there are 1 6 7 4 4 4 6 4 total ways of reading OOZYRATINASANITARYZOO