Solve the following calculations: a) 42, d) sqrt(25), g) 72, j) sqrt(64), m) 102, p) sqrt(121)

$$4^2 = 4 \times 4 = 16$$

The completed expression is:

$$4^2 = 4 \times 4 = \boxed{16}$$

$$\sqrt{25} = 5$$

The completed expression is:

$$\sqrt{25} = \boxed{5}$$

$$7^2 = 7 \times 7 = 49$$

The completed expression is:

$$7^2 = \boxed{49}$$

j)

$$\sqrt{64} = 8$$

The completed expression is:

$$\sqrt{64} = \boxed{8}$$

m)

$$10^2 = 10 \times 10 = 100$$

The completed expression is:

$$10^2 = \boxed{100}$$

p)

$$\sqrt{121} = 11$$

The completed expression is:

$$\sqrt{121} = \boxed{11}$$