hmm
depends if you shade in the square or outside the square
lets say we have a circle with radius 1
means that the area is pi1^2 or pi squre units
1 will be the length of 1/2 the diagonals of the square
meaning the area of the square is 2
so 2/pi is the fraction of the circle that is the square
2/pi≈63.66%
100-63.66=36.34
36.34% is what is outside the squrae
the closest number is 36.34 so I would think that is it
about 35%