Aiming at distinction

- Give me three distinct primes?
- In what ways distinct?
- Different.
- So you don’t want them to be easily perceived by the senses or intellect?
- Come again?
- Like in the expression ‘it had a distinct flavor.’
- No, I didn’t mean that. Just different would be fine.
- Should they be clearly defined?
- What?
- Like in the expression ‘at a distinct disadvantage.’
- No, thank you.
- To avoid any misunderstanding, did you have in mind that the primes should be very likely or probable?
- ?!
- Like in the expression ‘there is a distinct possibility that she won’t come.’
- I have a feeling that you are avoiding the problem.
- You are flattering me.
- So, will you give me three distinct primes?
- I am working on it.
- Good!
- One final clarification. Should the three primes be notable like in ‘it was a distinct honor and high privilege?’
- I have told you already. They should just be different. Forget distinct!
- When you say different, do you mean dissimilar, separate, various, or unusual?
- Try unusual!
- That’s a hard one. What about 11, 101, and 101111?
- Finally!
- Are they unusual enough?
- Add them and add to the sum their product.
- You mean 11 + 101 + 101111 + 11 * 101 * 101111?
- Exactly.
- I am done.
- Is the answer a prime?
- Any prime or an unusual one?

Problem source: Berkeley Math Circle Monthly Contest.

One Response to “Aiming at distinction”

  1. mathmom Says:

    No, it is always even (and greater than 2)

    if one of the primes is 2, then
    2 + oddPrime1 + oddPrime2 (even + odd + odd) is even
    and 2 * oddPrime1 + oddPrime2 is even
    and the sum of 2 evens is even

    if none of the primes is 2, the sum of 3 odd primes is odd, and the product of 3 odd primes is odd (no factor of 2) and the sum of 2 odds is always even

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