Irrational numbers are numbers that can't be written as a ratio
So in those numbers we have:
[tex]\begin{gathered} 0.454545\ldots=\frac{45}{99}\text{ } \\ 0.777\ldots=\frac{777}{999} \\ 0.3=\frac{3}{10} \\ \sqrt{5}\text{ =}2.236067977\ldots\text{.} \end{gathered}[/tex]So the answer is a square root of 5, for