If $x$ is positive and $x^2 = 729$, what is the value of $x$?
I need to find a positive number that, when squared, equals 729. I could try to guess and check, but that might take a long time and I might not find the exact value. I could also try to factor 729 and see if there is a perfect square among its factors. 729 is divisible by 3, so I can write it as $3 \times 243$. 243 is also divisible by 3, so I can write it as $3 \times 81$. 81 is a perfect square, it is $9^2$. So, 729 is $3 \times 3 \times 9^2$. I can simplify this by grouping the 3's together and writing it as $3^2 \times 9^2$. This means that 729 is the square of $3 \times 9$, which is 27. So, $x = 27$. 