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pokerfan Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 06:49 PM
Original message
A puzzle for the mathletes
A large, square, brick wall is one brick higher and one brick narrower than another wall. How many more bricks are in the first wall?
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suninvited Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 06:50 PM
Response to Original message
1. They are both square? nt
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pokerfan Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 06:53 PM
Response to Reply #1
2. one wall is 'one brick higher and one brick narrower'
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suninvited Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 06:53 PM
Response to Original message
3. Wouldn't they be equal.
I am no mathlete, thats for sure.
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pokerfan Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 06:53 PM
Response to Reply #3
4. nope
(but very close)
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suninvited Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 06:56 PM
Response to Reply #4
5. youre gonna make me get out the graph paper.
having never been a great math student, I still find I can solve a lot of math problems with graph paper.
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pokerfan Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 07:14 PM
Response to Reply #5
14. graph paper will get you there
4x4=16; 3x5=15
5x5=25; 4x6=24
6x6=36; 5x7=35
7x7=49; 6x9=48
8x8=64; 7x9=63
9x9=81; 8x10=80
10x10=100; 9x11=99
11x11=121; 10x12=120
12x12=144; 11x13=143

I first noticed this when I was memorizing multiplication tables back in third grade.

Anyway, this will be in Marilyn's column in Parade magazine this Sunday.
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KitchenWitch Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 06:57 PM
Response to Original message
6. Zero
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JVS Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 06:57 PM
Response to Original message
7. one
Let's just say that our big square is ten bricks high and ten long, for a total of 100. The other wall is only 9 bricks high but 11 bricks wide for 99.
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JVS Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 06:58 PM
Response to Reply #7
8. We can try it again for a wall that is 12x12
it is 144, one lower but wider is 13x11= 143, one less
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JVS Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 07:00 PM
Response to Reply #8
10. Let us generalize the form
Our square wall is always x bricks long and high for a total of x^2 bricks.

The wall it surpasses is always (x-1)*(x+1) bricks = x^2-1

It will always be one brick smaller
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suninvited Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 07:00 PM
Response to Reply #7
9. youre right and it works for any size
I had just figured it out, but you beat me to it.

I was using 9x9 opposed to 10x8.

Way to go.
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JVS Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 07:00 PM
Response to Reply #9
11. See number 10, I generalized it
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pokerfan Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 07:01 PM
Response to Reply #7
12. check out the big brain on JVS
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suninvited Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Dec-05-08 07:04 PM
Response to Reply #12
13. no kidding
he must have a giant head to hold all that.
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