one way is to factor and group and get every 3
729=3 times 3 times 3 times 3 times 3 times 3
so we group the ones that happen 3 times
729=(3*3*3) times (3*3*3)
we know that we can take the cube root of each group and multiply the result
729=[tex]( \sqrt[3]{3*3*3})( \sqrt[3]{3*3*3})[/tex]=(3)(3)=9
the answer is 9