Answer:
https://www.khanacademy.org
Step-by-step explanation:
Khan Academy is free and you can choose by grade level or course. It's a personalized learning experience with videos and practice exercises that includes progress tracking.
The number could be several different ones. Are you sure that's exactly what the problem says? If not, I'm going to ask you write the entire problem. If not, then whoever made it did not give enough information for there to be an absolute answer. I'm sorry I couldn't help you, but I really hope I can with more information.
I believe it is {sqr(1/8)/2} or 0.5*sqr(1/8)
Your answer is 1.3, i hope this helped, tell me if you need more help