# Incorrect answer - Mersenne primes **URL:** \ **Category:** Open Trivia DB\ **Created:** [April 7, 2020, 2:22pm UTC](https://forums.pixeltailgames.com/t/incorrect-answer-mersenne-primes/36782 "2020-04-07T14:22:34Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![pavelkomin](https://forums.pixeltailgames.com/letter_avatar_proxy/v4/letter/p/858c86/32.png) [@pavelkomin](https://forums.pixeltailgames.com/u/pavelkomin)\ **Post date:** [April 7, 2020, 2:22pm UTC](https://forums.pixeltailgames.com/t/incorrect-answer-mersenne-primes/36782/1 "2020-04-07T14:22:34Z")
Question ID 930: What is the first Mersenne prime over 1000? The answer given is 1,279, however this is the exponent in the Mersenne prime formula M(n) = 2^n − 1. 1,279 is not a Mersenne prime, neither of the given answers is. The correct answer should be 8191. [Wiki article with the list of Mersenne primes and their exponents](https://en.wikipedia.org/wiki/Mersenne_prime#List_of_known_Mersenne_primes) ---
**Author:** ![Mattio](https://forums.pixeltailgames.com/user_avatar/forums.pixeltailgames.com/mattio/32/32656_2.png) [@Mattio](https://forums.pixeltailgames.com/u/Mattio)\ **Post date:** [April 7, 2020, 6:09pm UTC](https://forums.pixeltailgames.com/t/incorrect-answer-mersenne-primes/36782/2 "2020-04-07T18:09:26Z")
This was actually mentioned previously in the post linked below some time ago. But it’s understandable you missed it because they actually put it into Trivia Suggestions instead of Open Trivia DB. Just thought I’d link it here too. > [@Errors In the Questions](https://forums.pixeltailgames.com/t/errors-in-the-questions/35004): > > I recently had a question about Mersenne primes. After getting the question wrong and looking up what they were I discovered an error in the question. The question was: What is the first Mersenne prime over 1000? The answer given was 1279. A Mersenne prime is a prime that is 1 less than a power of 2. 1280 is not a power of two. The question should read instead: What is the first exponent over 1000 that results in a Mersenne prime? ---
**Author:** ![pavelkomin](https://forums.pixeltailgames.com/letter_avatar_proxy/v4/letter/p/858c86/32.png) [@pavelkomin](https://forums.pixeltailgames.com/u/pavelkomin)\ **Post date:** [April 8, 2020, 10:07am UTC](https://forums.pixeltailgames.com/t/incorrect-answer-mersenne-primes/36782/3 "2020-04-08T10:07:55Z")
Yeah, but the post is almost half a year old and it is still ignored :{ While the others are resolved quite quickly ---
**Author:** ![Sabrina](https://forums.pixeltailgames.com/user_avatar/forums.pixeltailgames.com/sabrina/32/83818_2.png) [@Sabrina](https://forums.pixeltailgames.com/u/Sabrina)\ **Post date:** [April 8, 2020, 6:15pm UTC](https://forums.pixeltailgames.com/t/incorrect-answer-mersenne-primes/36782/4 "2020-04-08T18:15:18Z")
Sorry we never replied to the previous thread, the answer posted in that thread was the correct answer. > [@Errors In the Questions](https://forums.pixeltailgames.com/t/errors-in-the-questions/35004/2): > > In the table, _p_ is the exponent and _M_ _p_ is the actual prime number, the 15th number( _M_ p = 21279 - 1) would be the first Mersenne prime **exponent** over 1000, not the actual prime number which is 386 digits long. ---
**Author:** ![pavelkomin](https://forums.pixeltailgames.com/letter_avatar_proxy/v4/letter/p/858c86/32.png) [@pavelkomin](https://forums.pixeltailgames.com/u/pavelkomin)\ **Post date:** [April 8, 2020, 7:41pm UTC](https://forums.pixeltailgames.com/t/incorrect-answer-mersenne-primes/36782/5 "2020-04-08T19:41:36Z")
The question is still present incorrectly though. I just checked. ---
**Author:** ![Sabrina](https://forums.pixeltailgames.com/user_avatar/forums.pixeltailgames.com/sabrina/32/83818_2.png) [@Sabrina](https://forums.pixeltailgames.com/u/Sabrina)\ **Post date:** [April 8, 2020, 7:42pm UTC](https://forums.pixeltailgames.com/t/incorrect-answer-mersenne-primes/36782/6 "2020-04-08T19:42:29Z")
Which? ---
**Author:** ![pavelkomin](https://forums.pixeltailgames.com/letter_avatar_proxy/v4/letter/p/858c86/32.png) [@pavelkomin](https://forums.pixeltailgames.com/u/pavelkomin)\ **Post date:** [April 8, 2020, 7:43pm UTC](https://forums.pixeltailgames.com/t/incorrect-answer-mersenne-primes/36782/7 "2020-04-08T19:43:08Z")
ID 930 with the Mersenne primes. ---
**Author:** ![Sabrina](https://forums.pixeltailgames.com/user_avatar/forums.pixeltailgames.com/sabrina/32/83818_2.png) [@Sabrina](https://forums.pixeltailgames.com/u/Sabrina)\ **Post date:** [April 8, 2020, 7:44pm UTC](https://forums.pixeltailgames.com/t/incorrect-answer-mersenne-primes/36782/8 "2020-04-08T19:44:52Z")
The answer isn’t incorrect. The first Mersenne Prime over 1000 is M1279. The next mersenne prime in the sequence after M1279 is M2203. The last Mersenne Prime before 1000 is M607. ---
**Author:** ![pavelkomin](https://forums.pixeltailgames.com/letter_avatar_proxy/v4/letter/p/858c86/32.png) [@pavelkomin](https://forums.pixeltailgames.com/u/pavelkomin)\ **Post date:** [April 8, 2020, 7:50pm UTC](https://forums.pixeltailgames.com/t/incorrect-answer-mersenne-primes/36782/9 "2020-04-08T19:50:15Z")
M1279 is not 1279. M1279 is 386-digit number. The largest Mersenne prime larger than 1000 is 8191 (M13). It is explained in my post and in the linked post. ---
**Author:** ![MightyBalian](https://forums.pixeltailgames.com/user_avatar/forums.pixeltailgames.com/mightybalian/32/34283_2.png) [@MightyBalian](https://forums.pixeltailgames.com/u/MightyBalian)\ **Post date:** [April 8, 2020, 8:13pm UTC](https://forums.pixeltailgames.com/t/incorrect-answer-mersenne-primes/36782/10 "2020-04-08T20:13:24Z")
> [@Errors In the Questions](https://forums.pixeltailgames.com/t/errors-in-the-questions/35004/2): > > Sorry we never replied to the previous thread, the answer posted in that thread was the correct answer. > > > [@Errors In the Questions](https://forums.pixeltailgames.com/t/errors-in-the-questions/35004/2): > > > > In the table, _p_ is the exponent and _M_ _p_ is the actual prime number, the 15th number( _M_ p = 21279 - 1) would be the first Mersenne prime **exponent** over 1000, not the actual prime number which is 386 digits long. That post you just linked proves you wrong, though. 1279 is the first Mersenne exponent over 1000, not the first Mersenne prime. The first Mersenne prime over 1000 is 8191. ---
**Author:** ![Sabrina](https://forums.pixeltailgames.com/user_avatar/forums.pixeltailgames.com/sabrina/32/83818_2.png) [@Sabrina](https://forums.pixeltailgames.com/u/Sabrina)\ **Post date:** [April 8, 2020, 8:37pm UTC](https://forums.pixeltailgames.com/t/incorrect-answer-mersenne-primes/36782/11 "2020-04-08T20:37:37Z")
The question’s wording has been adjusted.