Is 3 square roof of 512 a rational irrational or a nonreal number?

The expression "3 square roof of 512" seems to refer to (3 \sqrt{512}). Since (512) can be simplified to (16 \times 32), and thus (\sqrt{512} = 16\sqrt{2}), the entire expression equals (3 \times 16\sqrt{2} = 48\sqrt{2}). Since (\sqrt{2}) is an irrational number, (48\sqrt{2}) is also irrational. Therefore, the answer is that (3 \sqrt{512}) is an irrational number.