Find the square root of 16.

$$\sqrt{16} = 4$$

The completed expression is:

$$\sqrt{16} = \boxed{4}$$

$$5^2 = 5 \times 5 = 25$$

The completed expression is:

$$5^2 = 5 \times 5 = \boxed{25}$$

$$6^2 = 6 \times 6 = 36$$

The completed expression is:

$$6^2 = 6 \times 6 = \boxed{36}$$

$$\sqrt{36} = 6$$

The completed expression is:

$$\sqrt{36} = \boxed{6}$$

$$\sqrt{49} = 7$$

The completed expression is:

$$\sqrt{49} = \boxed{7}$$

$$8^2 = 8 \times 8 = 64$$

The completed expression is:

$$8^2 = \boxed{64}$$

k)

$$9^2 = 9 \times 9 = 81$$

The completed expression is:

$$9^2 = \boxed{81}$$

l)

$$\sqrt{81} = 9$$

The completed expression is:

$$\sqrt{81} = \boxed{9}$$

n)

$$\sqrt{100} = 10$$

The completed expression is:

$$\sqrt{100} = \boxed{10}$$

o)

$$11^2 = 11 \times 11 = 121$$

The completed expression is:

$$11^2 = \boxed{121}$$

q)

$$12^2 = 12 \times 12 = 144$$

The completed expression is:

$$12^2 = \boxed{144}$$

r)

$$\sqrt{144} = 12$$

The completed expression is:

$$\sqrt{144} = \boxed{12}$$