If you have got your PPL on the way to getting sponsorship then, well done but keep using the CRP 5. 95% in the PPL Nav well done, I got 84% in the ATPL Nav and my CRP 5 nearly melted it was used that much. The more you use it the better it gets!(like many things in life!)It will also teach you rules of thumb to apply. You cant use formula in the exams you just dont have the time.
If you are just carrying on at PPL level then use any way you like as long as it gets the right answer.