A puzzle for the mathletes
pokerfan
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Fri Dec-05-08 07:49 PM
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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?
suninvited
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Fri Dec-05-08 07:50 PM
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1. They are both square? nt
pokerfan
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Fri Dec-05-08 07:53 PM
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2. one wall is 'one brick higher and one brick narrower'
suninvited
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Fri Dec-05-08 07:53 PM
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3. Wouldn't they be equal.
I am no mathlete, thats for sure.
pokerfan
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Fri Dec-05-08 07:53 PM
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suninvited
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Fri Dec-05-08 07:56 PM
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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.
pokerfan
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Fri Dec-05-08 08:14 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.
KitchenWitch
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Fri Dec-05-08 07:57 PM
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JVS
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Fri Dec-05-08 07:57 PM
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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.
JVS
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Fri Dec-05-08 07:58 PM
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8. We can try it again for a wall that is 12x12
it is 144, one lower but wider is 13x11= 143, one less
JVS
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Fri Dec-05-08 08:00 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
suninvited
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Fri Dec-05-08 08:00 PM
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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.
JVS
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Fri Dec-05-08 08:00 PM
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11. See number 10, I generalized it
pokerfan
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Fri Dec-05-08 08:01 PM
Response to Reply #7
12. check out the big brain on JVS
suninvited
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Fri Dec-05-08 08:04 PM
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he must have a giant head to hold all that.
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