Answer:
c = 500,000
This is 6 digit number with 5 zero's.
We just multiply the radius ^2 by pi
D = 800m R = 400
R^2 = 400 x 400 = 160000
A = 160000π = 502654.824574
We estimate from 160000 and just count the 0's on multiplication as long as the 10's don't change in that estimation.
we can show the workings as the counting loops under the 6 and 0's of 160000. = 5 units+ 1.
= 500,000 m^2
1 [- - - - -} = 500000
