Brain Teasers
A Pleasing Number
Which two closest together whole numbers that, when multiplied, produce the pleasant looking number: 1234567890 ?
Answer
34,227 and 36,070.The only factors of 1234567890 are 2, 3, 3, 5, 3607 and 3803. Testing the various products of these factors reveals that 34,227 and 36,070 are the closest pair of numbers that produce 1234567890.
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
Those are just the prime factors. It would be
pretty hard to do this one without a factoring program
(like the Unix program "factor"), since the two largest
prime factors would be a lot of work to find by hand.
But given that factoring, I noted that the two large prime factors
were so close together that you really just wanted to find the closest
grouping of the small factors to multiply them. That gives 9 and 10 for the
best grouping of the small factors, and the answer follows.
pretty hard to do this one without a factoring program
(like the Unix program "factor"), since the two largest
prime factors would be a lot of work to find by hand.
But given that factoring, I noted that the two large prime factors
were so close together that you really just wanted to find the closest
grouping of the small factors to multiply them. That gives 9 and 10 for the
best grouping of the small factors, and the answer follows.
Yeah, once I had the prime factors I saw I could make 9 and 10 with the rest, so 10 * the smaller and 9 times the larger of the other two factors.
Once I got down to 13717421 and had tried the primes up to 100 I used the online factorization calculator at http://www.mathwarehouse.com/ arithmetic/numbers/prime-number/ prime-factorization-calculator.php to factor the rest.
Once I got down to 13717421 and had tried the primes up to 100 I used the online factorization calculator at http://www.mathwarehouse.com/ arithmetic/numbers/prime-number/ prime-factorization-calculator.php to factor the rest.
The (really simple) scip model that I used to solve this teaser can be found at
https://pastebin.com/QUMU2mGU
https://pastebin.com/QUMU2mGU
To post a comment, please create an account and sign in.
Follow Braingle!