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| 0 user currently in Brain Teasers. | 2 guests |
| Acmlm's Board - I2 Archive - Brain Teasers - Another math puzzle |
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Heian-794 Red Super Koopa Level: 44 Posts: 112/896 EXP: 611014 For next: 271 Since: 06-01-04 From: Kyoto, Japan Since last post: 21 days Last activity: 10 days |
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| Here's another math puzzle (this one from Japan), which is popular with people sitting on trains staring at the four digits on their tickets. It's a good one, and the solutions are straightforward but devious. Here goes: Using any mathematical symbols you desire, get each of the following strings of numbers to equal 10. 1 1 1 1 = 10 2 2 2 2 = 10 3 3 3 3 = 10 4 4 4 4 = 10 5 5 5 5 = 10 6 6 6 6 = 10 7 7 7 7 = 10 8 8 8 8 = 10 9 9 9 9 = 10 You can't write any letters or numbers, but you can use any symbol (plus, minus, parentheses, factorial, etc.) you wish. You don't have to insert anything between digits, so, for example, 2 2 can be read as twenty-two. Each problem must be solved a different way, which means that if you should stumble onto a solution that works for all nine problems, use it as your bingo-style "free space" for the one that you can't otherwise get. Here's a solution to the first one: (1 1 - 1) x 1 = 10 |
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JJ64 Boo Level: 45 Posts: 376/919 EXP: 640956 For next: 19208 Since: 05-22-04 From: Green Bay, WI Since last post: 441 days Last activity: 269 days |
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| (2 x 2 x 2) + 2 = 10 (3 / 3) + (3 x 3) = 10 (4 4 - 4) / 4 = 10 5 + 5 + 5 - 5= 10 That's all I could come up with for now. |
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neotransotaku Baby Mario 戻れたら、 誰も気が付く Level: 87 Posts: 770/4016 EXP: 6220548 For next: 172226 Since: 03-15-04 From: Outside of Time/Space Since last post: 11 hours Last activity: 1 hour |
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| (9 9 - 9) / 9 = 10 | |||
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DarkSlaya POOOOOOOOOOOORN! Level: 88 Posts: 235/4249 EXP: 6409254 For next: 241410 Since: 05-16-04 From: Montreal, Quebec, Canada Since last post: 8 hours Last activity: 5 hours |
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| (8 + 8)/ 8 + 8 = 10 (edited by DarkSlaya on 06-16-04 08:46 PM) (edited by DarkSlaya on 06-16-04 08:47 PM) |
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APH Striker Spiny Level: 37  Posts: 196/579 EXP: 321882 For next: 16371 Since: 05-17-04 From: Tacoma, WA Since last post: 58 days Last activity: 58 days |
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| (66 - 6) divided by 6 = 10. (77 - 7) divided by 7 = 10. you can do this with all of them. (2x-x) divided by x = 10. It's a law of arithmetic! (edited by APH Striker on 06-19-04 11:03 PM) (edited by APH Striker on 06-20-04 12:49 PM) |
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Heian-794 Red Super Koopa Level: 44 Posts: 140/896 EXP: 611014 For next: 271 Since: 06-01-04 From: Kyoto, Japan Since last post: 21 days Last activity: 10 days |
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| Neotransotaku and APH Striker, this is why I said: Each problem must be solved a different way, which means that if you should stumble onto a solution that works for all nine problems, use it as your bingo-style "free space" for the one that you can't otherwise get. Yes indeed, (11x - x) / x does indeed reduce to 10 since the Xs cancel.  Points: I realized I neglected to create a point system, and I'm going to assign between 1 and 9 points depending on difficulty. 6, 8, 9, 4, 5, 3, 2, 1 are worth 8, 7, 6, 5, 4, 3, 2, 1 respectively. I myself can't find a unique solution for 7, so that's worth 9 points. The freebie is worth 1. So JJ64 scores for 2, 3, and 5: total 9 DarkSlaya scores for 8: total 7 (and your solution is vastly simpler than mine, which was: (edited by Heian-794 on 06-24-04 12:44 PM) |
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rubixcuber Red Goomba Level: 12 Posts: 29/46 EXP: 6125 For next: 1796 Since: 10-13-04 From: St. Louis, MO USA Since last post: 331 days Last activity: 293 days |
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| (11-1)*1=10 2*2*2+2=10 3*3+3/3=10 4*4-4-sqrt(4)=10 (5+5)*5/5=10 ceiling(ln(6*6+6)+6)=10 ceiling(ln(7)+7+7/7)=10 8+(8+8)/8=10 floor(ln(9)+9-9/9)=10 (edited by rubixcuber on 11-21-04 01:24 AM) |
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Heian-794 Red Super Koopa Level: 44 Posts: 546/896 EXP: 611014 For next: 271 Since: 06-01-04 From: Kyoto, Japan Since last post: 21 days Last activity: 10 days |
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| Are those answers with natural logs exact, Rubixcuber? | |||
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rubixcuber Red Goomba Level: 12 Posts: 30/46 EXP: 6125 For next: 1796 Since: 10-13-04 From: St. Louis, MO USA Since last post: 331 days Last activity: 293 days |
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| They are exact since I used ceiling and floor. Those are standard mathematical symbols. I'd have to think they are at least as valid as using the square root as a symbol. (edited by rubixcuber on 11-21-04 12:16 PM) |
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solusion Newcomer Level: 1 Posts: 1/1 EXP: 9 For next: 2 Since: 08-04-05 Since last post: 90 days Last activity: 89 days |
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| hey i think i ve got other solns for the 6 s : (( 6! )/6 )/( 6+6) for the 9: (9to the power(9 - 9))+9... well for the seven.. ((7/7)7) - 7 (in other words 17-7=10...).  . |
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Colleen Administrator Level: 136 Posts: 9654/11302 EXP: 29369328 For next: 727587 Since: 03-15-04 From: LaSalle, Quebec, Canada Since last post: 3 hours Last activity: 1 hour |
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| Please don't bump ancient, nine-month old threads. Thank you. |
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