Factor $20=2^{2}\times 5$. Rewrite the square root of the product $\sqrt{2^{2}\times 5}$ as the product of square roots $\sqrt{2^{2}}\sqrt{5}$. Take the square root of $2^{2}$.
$$2\sqrt{5}\sqrt{125}\sqrt{45}$$
Factor $125=5^{2}\times 5$. Rewrite the square root of the product $\sqrt{5^{2}\times 5}$ as the product of square roots $\sqrt{5^{2}}\sqrt{5}$. Take the square root of $5^{2}$.
$$2\sqrt{5}\times 5\sqrt{5}\sqrt{45}$$
Multiply $2$ and $5$ to get $10$.
$$10\sqrt{5}\sqrt{5}\sqrt{45}$$
Multiply $\sqrt{5}$ and $\sqrt{5}$ to get $5$.
$$10\times 5\sqrt{45}$$
Factor $45=3^{2}\times 5$. Rewrite the square root of the product $\sqrt{3^{2}\times 5}$ as the product of square roots $\sqrt{3^{2}}\sqrt{5}$. Take the square root of $3^{2}$.
