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You need to be systematic.
Try with a smaller number of cards first or using two sets of cards one to help you keep your "magic" cards in the correct positions.
Can you design a new shape for the twenty-eight squares and arrange the numbers in a logical way? What patterns do you notice?
In a square in which the houses are evenly spaced, numbers 3 and 10 are opposite each other. What is the smallest and what is the largest possible number of houses in the square?
Exactly 195 digits have been used to number the pages in a book. How many pages does the book have?