1. The problem asks: "45 is which square?" This means we want to find if 45 is a perfect square, and if so, which number squared equals 45. 2. The formula for a perfect square is: $$n^2 = x$$ where $n$ is an integer and $x$ is the number we want to check. 3. To check if 45 is a perfect square, we find the square root of 45: $$\sqrt{45} = \sqrt{9 \times 5} = \sqrt{9} \times \sqrt{5} = 3 \times \sqrt{5} \approx 6.708$$ 4. Since $\sqrt{45}$ is not an integer, 45 is not a perfect square. 5. However, 45 is between the perfect squares $6^2 = 36$ and $7^2 = 49$. 6. Therefore, 45 is not a perfect square, but it lies between the squares of 6 and 7. Final answer: 45 is not a perfect square.