How to determine the circumference and area of a circle if the radius of the circle is reduced by 2 times?

The circumference is equal to:
C = 6.28 * R, where R is the radius of the circle.
If we now reduce the radius by half, then the circle will accordingly also be halved, since the circumference of the circle linearly corresponds to the radius:
C = 6.28 * R> 6.28 * R / 2 twice.
The area of the circle is:
S = 3.14 * R², if the radius is reduced by half, then the area will decrease by four times, since here we are dealing with a quadratic dependence:
S = 3.14 * R²> 3.14 * R² / 4 four times.