KöMaL 2014 K411

The power $x^5$ cannot only be calculated by doing the multiplication $x^. x^. x^. x^. x$, but also with fewer multiplications, by calculating partial results (e.g. $y$=$x^. x$) and obtaining the final answer by multiplying those: $y^. y^. x$, which only makes three multiplications altogether. Express the power $x^{23}$ with less than 10 multiplications to carry out.