Calculate with a calculator. Which number fits in place of [[$ x $]]?

a) [[$ \sqrt {x} = 4 $]]

[[$ x = $]]

b) [[$ \sqrt {x} = 7 $]]

[[$ x = $]]

c) [[$ \sqrt {169} = x $]]

[[$ x = $]]

d) [[$ \sqrt {x} = 19 $]]

[[$ x = $]]

e) [[$ \sqrt {x} = 0,16 $]]

[[$ x = $]]