Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

BTaylor Group Title

Arrange these seven numbers and eight dots ( --> . ) .4.5.6.7.8.9.0. so they add up to eighty two.

  • 2 years ago
  • 2 years ago

  • This Question is Closed
  1. BTaylor Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    can you help with this? @Calcmathlete @agentx5

    • 2 years ago
  2. agentx5 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Are the dots representing comma separated values (i.e. a sequence), decimal points, or \(\large \cdot\) for multiplication?

    • 2 years ago
  3. BTaylor Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    they can be any dot in math operations. decimals, multiplication, repeating numbers, anything else?

    • 2 years ago
  4. agentx5 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Oh... so we can choose the operand we want? :-3 I would recommend starting with the prime factorization of 82 in that case, can you do this step? :-)

    • 2 years ago
  5. BTaylor Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    82 = 2 x 41

    • 2 years ago
  6. agentx5 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Yep, and right away we can see that's only going to help us so far because 41 is prime. So now for the listing of addition/subtraction options using our "factors" from the list 8*9 = 72 7*9 = 63 etc... We can see that won't be good either because brute force method here is going to be 823543 possible combos... Yeah no. Ok for computers, not good for neuron cells. So getting creative... I'm going to try to minimize each product, and because of symmetry they're all going to be even (which we'll need for 82): 4*9 = 36 5*8 = 40 6*7 = 42 Hmm so 5*8 + 6*7 = 82 But did we have to use all of these?

    • 2 years ago
  7. agentx5 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    If so, it will get even more complicated because you'll be needing to use subtraction as well, or you will break 82 (think of a game of BlackJack, aka. 21, if you need a parallel as to why)

    • 2 years ago
  8. BTaylor Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    OK. I googled the question. It turns out that it is an old problem. http://www.mathsisfun.com/puzzles/our-columbus-problem.html I would've never gotten that!

    • 2 years ago
  9. agentx5 Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Critical need-to-know information I was missing in the question: "The dot over a number signifies that it is a repeater which would go on for ever" >_< Tough puzzle though!

    • 2 years ago
  10. BTaylor Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    nice try.

    • 2 years ago
    • Attachments:

See more questions >>>

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.