Feature Request

I notice some features like permutation (nPr), nth root (instead of √) and percentage (%) are missing, but are common in other scientific calculators, in the current version. Please add these features

You can use _n_th root by using 1/n exponent and percentage without % by multiply it by 0.n but not for permutation without re-writing the whole formula for nPr. It was the most important among the 3 suggested feature