a. B, C are prime numbers, and a + B = 33, B + C = 44, C + D = 66, then CD=______ .

a. B, C are prime numbers, and a + B = 33, B + C = 44, C + D = 66, then CD=______ .

Because there is only one even prime number 2 in all prime numbers, the sum of a + B = 33 is odd, B + C = 44, C + D = 66, and the sum of these two is even, so if a = 2, then B = 33-2 = 31; C = 44-31 = 13; d = 66-13 = 53; so CD = 53 × 13 = 689