Express each of the following numbers as the sum of three odd primes:
(a) 21 (b) 31
(c) 53 (d) 61
(a) 21 = 5 + 5 + 11
Clearly, 5 and 11 are prime numbers.
(b) 31 = 5 + 7 + 19
Clearly, 3, 7 and 19 are prime numbers.
(c) 53 = 5 + 17 + 31
Clearly, 5, 17 and 31 are prime numbers.
(d) 61 = 13 + 17 + 31
Clearly, 13, 17 and 31 are prime numbers.