In order to answer this, it would be useful to calculate the area of the cardboard and the circles. We do as follows:
Total area of cardboard = 8.0 in. x 11.0 in = 88 in^2
Area of one circle = pi(r^2) = pi(0.5)^2 = 0.7854 in^2
Number of full circles = 88 / 0.7854 = 112.0451
Therefore, there will be 112 number of full circles. The percentage of waste is equal to:
% waste = (88 - 0.7854(112) / 88) x 100= 0.04%