Answer:
20 to the 5th power
Step-by-step explanation:
When given the scale factor, just multiply!
8cm * 2.5 = 20cm per side
There are many possible factors:

Hope this helps!!
Answer:
65.9734457254 or 65.97
Step-by-step explanation:
c= pi x diameter
c= pi x (10.5 x 2)
c= pi x 21
= 65.9734457254