Hi! I Am Learning About How To Evaluate Radical Expressions

hi! I am learning about how to evaluate radical expressions to check out my daughter's homework, I asked my daughter how she got the answer in some expression and she said that she just was playing with the calculator until she got the answer but I wonder if there is an easiest and quickest way how to solve it. for example on this radical the radicand is 729 and the index is 3 how do I figure out that the answer is 9