15 October 2008

Another math puzzle


Using conventional American coins - pennies, nickels, dimes, and quarters, what is the most money that you can have in your pocket and still be unable to give exact change for a dollar?

Answer in the "comments" section - but don't look there until you come up with an answer that's considerably higher than a dollar...

7 comments:

  1. The most you can have is $1.19, consisting of three quarters, four dimes, and four pennies.

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  2. Woohoo! I got it. :)

    You can also do 1 quarter, 9 dimes, and 4 pennies. Same total amount.

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  3. Certainly. Or instead of substituting five dimes for two of the quarters you can substitute a variety of nickels for some of the dimes. The precise combination is not unique, but the max total value is. Kudos on solving it.

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  4. Don't know how I ran across this old post, but anyway...
    If you swap out for nickels instead of dimes though, you *can* make a dollar change. For instance, IF you had that 1 quarter, 9 dimes and 4 pennies and changed out a dime for 2 nickels, then that quarter + a nickel + 7 of the dimes makes exactly $1.00. Same if you have any nickels in the 3-quarter option...because the nickel + a quarter comes out to a multiple of 10 cents, dimes will round out an even dollar.

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  5. Jennifer, you're correct, but that wasn't the point of the puzzle. The question was to figure out how much money (what combination of coins) you could have and still NOT be able to give someone exact change for a buck.

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  6. Minnesotastan is missing Jennifer's point.

    Minnesotastan said:
    "you can substitute a variety of nickels for some of the dimes."

    If you have nickles, you won't make it to $1.19 and still not be able to make change.

    ReplyDelete
  7. You're right. I thought Jennifer was responding to the post, but she was responding to my comment - which was mathematically wrong.

    Rather than delete the comment (which would leave the comments stranded without a reference, I'll leave the thread intact as an object lesson.

    tx.

    ReplyDelete

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