For people in 7th grade struggling with Circle (Radius - Diameter - Circumference)
Here's a picture that can help! I was just helping one of my friends! Please don't remove this Brainly <3

How it works it we do Radius x 2 when we try to find the Diameter!
Because Radius is always half of the Diameter.
Then we do Diameter x Pi which is (D x 3.14) Pi = 3.14 so thats why we do Diameter x 3.14 for anybody wondering!
Then after we do the Diameter x 3.14 and we get our result we get the circumference!

To get area we do r2 (Your Radius to the second power x Pi (3.14) )

Then whatever you get is your area :D