1. ## Math Challenged

The game is a math game, we start out with a simple math question then whoever answers it has to come up with a slightly harder question. Ok what is 12x12?

2. Member
Join Date
Jul 2007
Posts
29
144

ok
(17x4)+37

3. Okay, 105.

Now, what is the square root of 0.1?

4. 0.316....

What is the last digit of the number 2007^2007?

5. 3?

6. Originally Posted by JMV
3?
Correctomunto!

You now have the honor of asking the next question, my friend.

7. Thank you.

8. 200-209

what is the smallest number which can be written as the sum of two (positive) cubes in two different ways?
except 2

9. I'll post the answer in 12 hours, for now I'll need to ask for the number to get a taxicab.
Last edited by The_Radiation_Specialist; 2007-Sep-18 at 02:04 PM. Reason: hints

I'll post the answer in 12 hours, for now I'll need to ask for the number to get a taxicab.
I've been meaning to ask: how was that a hint for 1729?

Anyway: What's the smallest number that, when squared, produces a four digit number comprised of two 2-digit primes.

e.g. 37^2 = 1369 -- thirteen is prime, but 69 isn't, so 37 isn't the answer.

11. http://en.wikipedia.org/wiki/1729_%28number%29
1729 = 1^3 + 12^3 = 9^3 + 10^3

Post a question anyone...

12. A rectangular floor is covered by square tiles. The tiles along the edge of the floor are red. The rest are white. There is an equal number of red and white tiles.

How many tiles are there?

13. 8x6

8x6
Very good. But is this the only possible answer? (Hint: No)

15. Originally Posted by DanishDynamite
Very good. But is this the only possible answer? (Hint: No)
8x6
12x5

l assume you do not consider 6x8 and 5x12 to be distinct from the above.

Do you also allow 0x0?

16. Established Member
Join Date
Apr 2007
Posts
762
Originally Posted by Homo Bibiens
8x6
12x5

l assume you do not consider 6x8 and 5x12 to be distinct from the above.

Do you also allow 0x0?
In general, where a=4(b-2)/(b-4) is a natural number for natural number b, the solution axb (or bxa) works.

17. Originally Posted by mr obvious
In general, where a=4(b-2)/(b-4) is a natural number for natural number b, the solution axb (or bxa) works.
I got them all, though, right?

a=4(b-2)/(b-4)

so

a=4+8/(b-4)

So 8 has to be divisible by (b-4). So that means b=0 or b=2 (which are "paired" solutions, and leave a floor with an area of zero), or b=5, b=6, b=8, or b=12.

18. Originally Posted by Homo Bibiens
8x6
12x5

l assume you do not consider 6x8 and 5x12 to be distinct from the above.

Do you also allow 0x0?
8X6 and 12X5 does it for me. Well done!

19. Nice, you need to post a slightly harder question now, TRS.

20. Using only three "9's" and any mathematical sign (+ - X / sqrt ^ ! etc) make it so that it can equal digits 1 to 10.

eg. for 1 you could write (9/9)^9

note there must be three "9's"

21. 1: (9/9)^9
2: (9+9)/9
3: sqrt (9*9/9)
4: sqrt(9) + 9/9
5: sqrt(9)!-9/9
6: (sqrt (9*9/9))!
7: sqrt(9) + 9/9
8: 9 - (9/9)
9: 9*9/9

edit: Thanks to Eroica for pointing out the missing factorial:
7: sqrt(9)! + 9/9

Coincidentally (re TRS's comment), I gave some thought to being a smart aleck and using 0.999... as the answer to "1", but since it used a "0", it technically would have been wrong.
Last edited by pghnative; 2007-Sep-21 at 12:46 PM. Reason: correct typo

22. Originally Posted by pghnative
7: sqrt(9) + 9/9
Just a typo, I think. He forgot the factorial sign:

(sqrt(9))! + 9/9 = 7

Aha! My math-fu is too weak...

24. 7: sqrt(9) + 9/9
?

more like 9-sqrt(9) + 0.9(recurring)

No Discussions about the validity of 0.999... = 1 ! I'm serious.

25. "69", dude!

Find the largest 51-digit number divisible by 11. (probably takes fewer keystrokes to describe the number than to type it out!)

Todd

26. I've been meaning to ask: how was that a hint for 1729?
Taxicab numbers

Find the largest 51-digit number divisible by 11.
999,999,999,999,999,999,999,999,999,999,999,999,99 9,999,999,999,990

27. I didn't count the 9s, but unless you miscounted, it's right.

Todd

28. How much dirt is there in a pentagonal prism-shaped hole with each side of the pentagon 1 meter and the depth 4 meters? Approximate to the nearest meter cube.

29. none

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