To get there long hand:
Take the diameter of 3.020 inches divided by 2 which equals 1.51 inches.
Square that result (1.51 times 1.51) equals 2.2801 square inches.
Take that result whcih really is the area of a square with 1.51 inch sides and multiply by pi which 3.1416 is close enough this equals 7.1632 square inches.
To get the volume; the area is multiplied by the depth so 7.1632 square inches times .080 inch equals .5731 cubic inches.
Conversion to cubic centimeters is 16.4 cubic centimeters to the cubic inch. So .5731 cubic inches times 16.4 cubic centimeters per cubic inch equals 9.3981 cubic centimeters.
This same pattern can be used to compute the swept area the piston makes in bore and stroke, it will compute the clearance volume of the piston crown to block deck, and it is used to roughly compute the volume of the head gasket. Head gaskets often aren't actually round, but the computation will be damn close.
Piston domes and combustion chambers need to be measured unless you're really adept at calculus and want to spend a day doing integrations, if not, buy a graduated cylinder and some colored alcohol.