Multiple choice general knowledge math & puzzles

How many pairs of prime numbers are there to express 18 as the sum of two prime numbers?

  1. 1

  2. 4

  3. 3

  4. 2
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D Correct answer
Explanation

There are only two ways to express 18 as the sum of two primes: 5 + 13 and 7 + 11. This is a specific case of Goldbach's conjecture, which states that every even number greater than 2 can be expressed as the sum of two primes.

AI explanation

18 can be written as the sum of two primes in exactly two ways: 5 + 13 and 7 + 11. Checking all prime pairs below 18 confirms no other combination sums to 18, matching the pattern described by Goldbach's conjecture for even numbers.

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