Answer:
587
Explanation:
If you look at the problem carefully, you will see that the question is basically just asking "what is the square root of 587 squared?" The square root and squared of something always cancel out, so the answer would be 587.
You could also just use your calculator. If you don't have one, your phone or computer should. Just plug it in and it will solve for you.
Hope this information helps. Please let me know if you need any more help!