I know that the answer is three and is easy to prove that like this: $$3=\sqrt{1+8}$$ $$ 3=\sqrt{1+2\sqrt{1+15}}$$ $$ 3=\sqrt{1+2\sqrt{1+3\sqrt{1+24}}}$$ $$...$$ but I wanted to know if there is any direct way of calculating the answer.
thanks in advance.