1. Express the surd as $\sqrt{\mathrm{Perfect\; square\; x\; a\; number}}$
2. $\sqrt{\mathrm{a\; x\; b}}$ = $\sqrt{a}$ x $\sqrt{b}$
3. $\sqrt{\mathrm{Perfect\; square\; x\; a\; number}}$ = $\sqrt{\mathrm{Perfect\; square}}$ x $\sqrt{\mathrm{a\; number}}$
4. $\sqrt{\mathrm{Perfect\; square}}$ = A number that when multiplied by itself gives the perfect square

Root of perfect squares

$\sqrt{4}$ = 2 since 2 x 2 = 4

$\sqrt{9}$ = 3 since 3 x 3 = 9

$\sqrt{\mathrm{16}}$ = 4 since 4 x 4 = 16

$\sqrt{\mathrm{25}}$ = 5 since 5 x 5 = 25

$\sqrt{\mathrm{36}}$ = 6 since 6 x 6 = 36

$\sqrt{\mathrm{49}}$ = 7 since 7 x 7 = 49

$\sqrt{\mathrm{64}}$ = 8 since 8 x 8 = 64

$\sqrt{\mathrm{81}}$ = 9 since 9 x 9 = 81

$\sqrt{\mathrm{100}}$ = 10 since 10 x 10 = 100

$\sqrt{\mathrm{121}}$ = 11 since 11 x 11 = 121

$\sqrt{\mathrm{144}}$ = 12 since 12 x 12 = 144

$\sqrt{\mathrm{169}}$ = 13 since 13 x 13 = 169

$\sqrt{\mathrm{196}}$ = 14 since 14 x 14 = 196

$\sqrt{\mathrm{225}}$ = 15 since 15 x 15 = 225