To solve the problem, you might think about the area of the square and in the fact that number of squares is always increasing since P2. You might consider:

1.- The number of squares increases at a specific rate.

2.-  The area of each square decreases as the number of squares increases at a specific rate, too.

When the trend is found, remember that a series is the sum of the terms in a sequence and in a convergent series the sum may be calculated in some types of series