2、The following is a calendar for May of a certain year. Using a $2 \times 2$ box that can frame four numbers (excluding Chinese characters), the number of different ways to frame four numbers is $\qquad$.

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Note: The original text includes a placeholder for the answer (indicated by $\qquad$). This has been preserved in the translation.
【Analysis】Find the pattern. We find: The number in the upper left corner of the square can be: $1,2,3 ; 5 \sim 10 ; 12 \sim 17 ; 19 \sim 23$ for a total of 20.