Brain Teasers
Food Fight Fiasco #2
The food fight is breaking out, and you are a prisoner. To determine if you really are the brain you claim you are, the other boss asks you the following with a 30-second time limit:
He writes down the following numbers:
1, 2, 3, 4, 5, 6, 7, 9, 2, 4, 3, 9, 1, 5.
The following numbers are used to create 7 distinct 2-digit prime numbers. Note that 1, 2, 3, 4, 5, and 9 must be used exactly twice while 6 and 7 must be used exactly once. What is the sum of those prime numbers?
He writes down the following numbers:
1, 2, 3, 4, 5, 6, 7, 9, 2, 4, 3, 9, 1, 5.
The following numbers are used to create 7 distinct 2-digit prime numbers. Note that 1, 2, 3, 4, 5, and 9 must be used exactly twice while 6 and 7 must be used exactly once. What is the sum of those prime numbers?
Hint
Note that any 2 digit number can be written as 10t+u, where t is the ten's digit, and u is the one's digit.Answer
3132, 4, and 6 cannot be in the one's place because that would make the number divisible by 2. 5 cannot also be in the ones place because that would make it divisible by 5. Thus, the sum of the primes is 10(2+4+5+6+2+4+5) + 1+3+7+9+1+3+9 = 313
It is also possible to figure out the prime numbers, although that will probably take longer than 30 seconds.
Hide Hint Show Hint Hide Answer Show Answer
What Next?
View a Similar Brain Teaser...
If you become a registered user you can vote on this brain teaser, keep track of which ones you have seen, and even make your own.
Solve a Puzzle
Comments
Well thought out, Mathie, just not my cup of tea. Nice job anyhow.
too easy!
Well, maybe you are so smart !
While I am not in any form questioning the logic, I do not think even the brightest person solves that puzzle in 30 seconds.
Especially if they are not preframed on the topic. Took me about 10 seconds just to get my head focused on the task.
Good teaser though!
Especially if they are not preframed on the topic. Took me about 10 seconds just to get my head focused on the task.
Good teaser though!
Nice bit of lateral thinking!
Excellent logic in your solution!
I isolated the ones and tens digits, but then went ahead and found the primes. Probably took a minute to do it that way.
The 30 seconds would be tough, but doable. Certainly I had the digits separated quick enough, I just missed the insight on the most efficient way to solve it.
I isolated the ones and tens digits, but then went ahead and found the primes. Probably took a minute to do it that way.
The 30 seconds would be tough, but doable. Certainly I had the digits separated quick enough, I just missed the insight on the most efficient way to solve it.
To post a comment, please create an account and sign in.
Follow Braingle!