In 1938, Skolem asked a question as to whether SL_n(Z) is polynomially parametrized. It was not until 2010 when Vaserstein positively answered this question. In joint work with Michael Larsen at Indiana University, we prove that SL_n(R) is also polynomially parametrized where R is the ring of integers in a number field. If time permits, I will discuss open problems around this type of question.