## Search found 1034 matches

- Tue Apr 04, 2006 11:16 pm
- Forum: Combinatorics
- Topic: No Ones
- Replies:
**1** - Views:
**2342**

### No Ones

Given that r is non-negative integer chosen at random and contains no more than n digits, what is the least value of n such that the probability of r containing no ones among its digits is less than 50%? What about less than 10%, 1%, p? What about containing no twos, threes, ... ? What about no zeros?

- Tue Apr 04, 2006 10:31 pm
- Forum: Combinatorics
- Topic: Lucky 7
- Replies:
**1** - Views:
**2247**

### Lucky 7

Given that n is a positive integer, find the probability that 2

^{n}ÃƒÂ¢Ã¢â€šÂ¬Ã¢â‚¬Å“ n^{2}is divisible by 7.- Tue Apr 04, 2006 8:00 pm
- Forum: Number Theory
- Topic: Mystery Function
- Replies:
**5** - Views:
**4468**

### Mystery Function

Explain what the following recursive function does, and why it works.

```
function mystery(x, y)
r = x mod y
if (r > 0) y = mystery(y, r)
return y
end function
```

- Tue Apr 04, 2006 5:05 pm
- Forum: News, Suggestions, and FAQ
- Topic: a Problem reading text
- Replies:
**1** - Views:
**2469**

Thanks for pointing that out ThomasH. I was re-writing part of the forum code that would allow easier (from my perspective) addition of new BBCode style symbols and it caused previous posts to not display properly. I thought I had gone through and fixed them all, but clearly I had missed one. All so...

- Tue Apr 04, 2006 5:02 pm
- Forum: Game Theory
- Topic: Shortest chess game
- Replies:
**19** - Views:
**12756**

Eighty, I hope you don't mind but I edited your post to replace the [ code ] section with [ tt ], as this offers monospacing and preservation of spaces without wrapping it in a code window. As a side issue I've now just discovered that [ code ] within [ hide ] doesn't function properly: the "Expand...

- Sun Apr 02, 2006 10:46 pm
- Forum: Recreational
- Topic: Active users??
- Replies:
**1** - Views:
**2689**

Active users include those who have solved at least one problem within 180 days AND newly registered users who have not yet solved any problems yet. However, if a user registers and does not solve at least one problem within 30 days then their account is "purged". The only reason I mention the numbe...

- Fri Mar 31, 2006 4:14 pm
- Forum: Applied Mathematics
- Topic: 0-60mph
- Replies:
**11** - Views:
**9146**

I guess that there are two types of problem that may appear in the "Applied Mathematics" forum: (i) problems for which parameters are given and the challenge is to acquire the correct model (whether it be statistical or relating to mechanics), or more difficult, (ii) problems for which neither the p...

- Thu Mar 30, 2006 7:27 am
- Forum: Recreational
- Topic: Missing Wedding Ring Finger
- Replies:
**15** - Views:
**12608**

- Wed Mar 29, 2006 11:52 pm
- Forum: Recreational
- Topic: Missing Wedding Ring Finger
- Replies:
**15** - Views:
**12608**

### Missing Wedding Ring Finger

The following lateral problem has tortured my sanity for many years now. It has a classic answer, and I have personally been through numerous other plausible answers, but I've been assured by a puzzle-meister that there is another answer. Even though I've still not discovered this "other answer" it ...

- Wed Mar 29, 2006 10:32 pm
- Forum: Number
- Topic: A mean radical puzzle
- Replies:
**2** - Views:
**3018**

Hi quintic, you may be interested to know that I've just added BBCode that allows some mathematical notation to be used; more to come! Check out the topic here:

http://mathschallenge.net/forum/viewtopic.php?t=48

http://mathschallenge.net/forum/viewtopic.php?t=48

- Wed Mar 29, 2006 10:05 pm
- Forum: Number
- Topic: Three ratios
- Replies:
**5** - Views:
**3821**

What an interesting result, quintic! That certainly works, rlblaster. An alternative approach... As a/b = r, a = br; similarly c=dr and e=fr. Numerator, N = 3a 2 c + 4c 3 e + 3e 2 c = 3(br) 2 dr + 4(dr) 3 fr + 3(fr) 2 dr = dr 3 (3b 2 + 4d 2 fr + 3f 2 ) Denominator, D = 3b 2 d + 4d 3 fr + 3f 2 d = d(...

- Tue Mar 28, 2006 11:32 pm
- Forum: Number Theory
- Topic: Numbers with Divisibility Conditions
- Replies:
**5** - Views:
**5961**

RogerHui, as this puzzle requires a computer to solve I've moved it to the Programming Problems section. Although it is borderline Combinatorics, the heart of the problem lies in analysis of divisibility, so I placed it in the Number Theory forum. By the way, what a challenging puzzle idea with a su...

- Mon Mar 27, 2006 5:06 pm
- Forum: News, Suggestions, and FAQ
- Topic: How Do I... Post Fixed Width Text?
- Replies:
**0** - Views:
**7967**

### How Do I... Post Fixed Width Text?

(Note that spaces need to be removed from BBCode tags to make them work. If in doubt click "Quote" and look at the code I used.) Fixed width tags are useful as they allow text to appear exactly as you wish. Normally extra spaces are stripped away, but in fixed width text everyting is preserved. This...

- Mon Mar 27, 2006 4:43 pm
- Forum: News, Suggestions, and FAQ
- Topic: How Do I... Hide Text?
- Replies:
**2** - Views:
**11310**

### How Do I... Hide Text?

(Note that spaces need to be removed from BBCode tags to make them work. If in doubt click "Quote" and look at the code I used.) Hiding text can be especially useful when you wish to post your solution to a problem and don't wish to influence the thinking of other members; a member needs to make a c...