To find the area of the square-shaped poster, we use the formula for the area of a square:

$A = s^2$

where $s$ is the length of one side. In this case, $s = 25$ inches.

$A = 25^2 = 625 \, \text{in}^2$

So, the area of the poster is 625 square inches.

Would you like me to explain any part of this in more detail?

Here are 5 related questions you might find interesting:

1. How would you calculate the area if the poster were a rectangle instead of a square?
2. What would be the perimeter of this square poster?
3. How much wall space would you need if you wanted to hang four of these posters together?
4. How does the area change if each side of the poster is doubled?
5. How do you convert square inches to square feet?

Tip: Always double-check your units when calculating area to ensure consistency.