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Re: QOTD#28 Which of the following CANNOT be the sum of two
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13 Oct 2016, 14:04
Explanation
Rather than listing out all of the prime numbers up to 43, stay focused on the unique number, 2, the only even prime number. All of the choices are odd, and two odd numbers would yield an even sum, so you’ll only be able to eliminate answers by adding 2 to an odd number. Each of the incorrect answers, therefore, is the sum of 2 and the previous prime number:
Choice A is 2 + 5;
choice B is 2 + 17;
choice D is 2 + 29; and
choice E is 2 + 41.
The answer is choice C.