Monday, November 26, 2012

A QUESTION THAT HAS TRULY PROVED UN-ANSWERABLE (so far)

Hi folks!

Well, it seems there is one question that really is stumping everyone:

What two decimal numbers can be multiplied times each other and create a product that is a whole number?


This was the "challenge" question on our mini-assessment last week, and lots of people got close... but no one quite got there.

Time to try this challenge again!

Your two numbers must be "decimal" numbers, also known as "non-integer numbers." When multiplied together, they must create a "whole" number, also known as an "integer number."

Decimal/ non-integer numbers are numbers like 0.45; 2.67; 3. 9; 0.005.



Whole/ integer numbers are numbers like 2, 6, 9, 10.

(integer numbers)


I will be posting hints throughout the week (Mr. Taylor had some interesting ideas about solving this one - yep, we discuss math at home. We are really that cool!).

Happy solving!

Post your solutions below. Be sure your solutions are DIFFERENT from the ones that appear before your answer, and be sure you can explain how your got your answer.

If you are feeling stumped, you can wait till I post a hint or two, and maybe that will be helpful.

Also, please keep posting on last week's post - it's the liveliest conversation we've had on the blog yet! So exciting!

Oh! Last but not least - keep an eye on the timestamps when you post a comment. I had a very interesting conversation with several of you today at dismissal about how the times are "off."
How much are they "off?" What time zone might our blog be set for? It's not our own...
(world time zone map)



34 comments:

  1. This comment has been removed by the author.

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  2. I figured it out. My cousin lives in california and and his time is pisific time

    Also when I posted above to see the time on the blog it was 5:32 and when I posted it the real time was 8:32.

    This Is Nathan

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  3. i forgot to say that my cousin is three hours behind my time

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  4. Great thinking, Nathan! Good work problem solving!

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  5. And now for the first clue for this week's question:
    For some folks, fraction form may be easier than decimal form.
    In thinking about that, remember that a fraction with the same numerator and denominator is equal to one whole.
    There will be another clue tomorrow.

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  6. Here is another clue...
    Or maybe 2 more?
    1. Remember how we talked about multiplying by a decimal making the number smaller? Hmm...
    2. Remember that decimals can be written as fractions, too...

    As always with very challenging questions, know that I am looking for you to try your best and use your resources. I don't expect a correct solution, but I do expect you to try!

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  7. Hi this is Raquel. I figured two out. I thought the opposite multiplication is division so I divided 1 by 0.012 and got 83.333333. Then I multiplied 83.333333 times 0.012 and got 1. On the other one I did 5 divided by 0.8 and got 6.25. Then I multiplied 6.25 times 0.8 and got 5.

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  8. Hi this is Raquel. The time I published my other post was 10:20 AM. The blog said I published on 7:19 AM. We are three hours ahead. When I looked on the time map three hours before us was in the west coast of the USA.

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  10. With my brothers help we guess and checked intill we came up with 5.2*2.5 witch equals 13

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    Replies
    1. Cool, good thinking!
      ...why do you think that works? What is special about those numbers?

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  11. Hi it's Posey,
    I thank Raquel for her strategy, it is very useful. I divided a whole number by a decimal; I got 5 divided by 1.5 equals 3.3 repeating. Then I did 5 divided by 1.6 and I got 3.125. Once I divided I checked it by multiplying the quotient and the divisor and seeing if it was the divined, it all worked out! Therefore you can multiply 2 decimals and get a whole number.

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  12. Hi it's Posey,
    The time zone that the blog is on right now is the Pacific Time Zone (three hours behind us).

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  13. Hi it's Jaelyn,
    I also used Raquel's strategy as well. I used the number 5 as my whole number to get to.I did 5 divided by 0.016 and got 312.5,multiplied that by 0.016 again and got 5. This was really easy ounce you actually got the concept of what your doing in percentages,decimals,fractions,and many more methods that can be used.

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  14. Hi it's Allie.
    So first I took the number 5 and divided it by 0.65 and got 7.6923076. Then I multiplied 7.6923076 times 0.65 and got 5. I also used Raquel's strategy and it was very helpful.

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  15. Hi it's jaelyn again,
    The answer to the time zones question is 3 hours because my blog post said 12:52pm and my clock said 3:52pm so yay,which by the time zones map is Pacific time.

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  16. Yay it's Jaelyn 1 more time. I just wanted to say thanks Raquel so much for your strategy it was very useful and helpful at the same time too.

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    Replies
    1. I agree, it is a great strategy and she really explained it well.

      ...hmmm... are there any cases where it wouldn't work? Why or why not?

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  17. Hi It's Allie.
    My post said it was 12:53pm and the time was 3:53. So it was the Pacific coast time. I have a friend who lives in San Diego, CA and i have to realize when i call her it is 3 hours earlier there.

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  18. Replies
    1. I tryed yours Caleb and I got 0.1 ???????????

      Nathan was here

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    2. Interesting. Any ideas on how to build on this thinking to find a set of two decimals that will work?

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  19. Drew here with this weeks blog assignment.

    For the math I did 0.25x96 and that equaled 24.Another one could be 0.02x50 which equals 1.

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    Replies
    1. Ah, yes, true, however - in both cases, one number you are multiplying is actually a whole number!

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  20. Drew here again.

    Like Nathan said, it is pacific time because, have you ever heard 8:00 7:00 central.Well you would probably hear 8:00 5:00 pacific if we lived right next to the states where pacific time is.

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  21. Hi. This is Rachel. I also used Raquel's strategy and I reverse engineered the problem. I discovered that 1.2 x 2.5 = 3.

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  22. EXCELLENT thinking, everyone!!! Thank you for your hard work! I like how you built off one another's thinking, as well!

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