To determine the number of squares needed to make the 28th picture, we need to identify the pattern in the number of squares in each picture. Based on the context, this likely refers to a sequence where the number of squares in each successive picture follows a consistent growth pattern.

Without specific details on the previous pictures, it's common in such problems for the sequence to follow a quadratic or arithmetic pattern (e.g., 1, 4, 9, 16, etc., where the number of squares follows the sequence of perfect squares, or something like 1, 2, 3, 4 squares per picture).

Could you provide more context or details about how the squares increase across the pictures? For instance, does the number of squares follow a square number pattern (1, 4, 9, 16, ...), or is it something else like a linear progression? That will help me determine the formula and answer accurately.