`a, 73^2 - 27^2 = ( 73 + 27 ) . ( 73 - 27 ) = 100 . 46 = 4600`
`b, 37^2 - 13^2 = ( 37 + 13 ) . ( 37 - 13 ) = 50 . 24 = 50 . 2 . 12 = 100 . 12 = 1200`
`c, 2002^2 - 2^2 = ( 2002 + 2 ) . ( 2002 - 2 ) = 2004 . 2000 = 2004 . 2 . 1000 = 4008 . 1000 = 4008000`