How many years?

Alternatively (to the difference of two squares formula), we can use the square of a sum formula:

$2025 = 45^2$

The next perfect square is:

$46^2 = (45 + 1)^2 = 45^2 + (2× 1 × 45 + 1) = 2025 + \boxed {91}$

Use the difference in squares formula. The square root of 2025 is 45. The next number is 46. 46 squared - 45 squared = (46-45)(46+45) = (1)(91). Therefore, the answer is 91 years after 2025.

The trick in recognizing perfect squares ending in 25 is if the preceding digits are the product of 2 consecutive integers, since (10t + 5)^2 = 100t^2 + 100t + 25 = 100 (t) (t + 1) + 25. In this case, t = 4, and 2025 = 45^2. The next perfect square year would be 46^2, which is 46^2 - 45^2 years from now , or (46 - 45)(46 + 45) = 91.