first find the area of the pizza:
area = PI x r^2
diameter = 16 inches...radius = 16 /2 =8 inches
area = 3.14 x 8^2 = 3.14 x 64 = 200.96 sq inches. Round to 201 square inches
the pizza has 6 calories per square inch so now multiple the total square inches by 6 to get total calories:
201 * 6 = 1206 total calories
now divide total calories by 144 to find the number of slices:
1206 / 144 = 8.375 so the pizza can be cut into 8 slices and each slice would have a little over 144 calories