a) $\sqrt{28}=\sqrt{4\cdot 7}=\sqrt{4}\cdot \sqrt{7}=2\sqrt{7}$

b) $\sqrt{32}=\sqrt{16\cdot 2}=\sqrt{16}\cdot \sqrt{2}=4\sqrt{2}$

c) $\sqrt{500}=\sqrt{100\cdot 5}=\sqrt{100}\cdot \sqrt{5}=10\sqrt{5}$

d) $\sqrt{810}=\sqrt{81\cdot 10}=\sqrt{81}\cdot \sqrt{10}=9\sqrt{10}$

e) $\sqrt{99}=\sqrt{9\cdot 11}=\sqrt{9}\cdot \sqrt{11}=3\sqrt{11}$

f) $\sqrt{80}=\sqrt{16\cdot 5}=\sqrt{16}\cdot \sqrt{5}=4\sqrt{5}$

g) $\sqrt{176}=\sqrt{16\cdot 11}=\sqrt{16}\cdot \sqrt{11}=4\sqrt{11}$

h) $\sqrt{12500}=\sqrt{2500\cdot 5}=\sqrt{2500}\cdot \sqrt{5}=50\sqrt{5}$