# Riddles/Math/Logic

This is a discussion on Riddles/Math/Logic within the A Brief History of Cprogramming.com forums, part of the Community Boards category; why not...

1. why not

2. As soon as you take some dirt out it's a whole hole

3. yup, that's the right answer ken and drive.

4. See, I'm not completly stupid.
Riddle: (easy one)
The Pope has it but he does not use it. Your father has it but your mother uses it. Nuns do not need it. Your lady friend's husband has it and she uses it. What is it?

5. Originally posted by Driveway
See, I'm not completly stupid.
Riddle: (easy one)
The Pope has it but he does not use it. Your father has it but your mother uses it. Nuns do not need it. Your lady friend's husband has it and she uses it. What is it?
a penis.

6. Better than the real answer, but no

7. My riddle: (I gave up on the other one)

A hunter sets out from camp at 4 o'clock in the morning with a compass. According to the compass, he travels due south for 4 hours. At that time he sees a bear and kills it (he is a hunter after all). He drags the bear with him for 4 hours due east, and he takes a quick break. Then he drags the bear due north for 4 hours at which time he arrives back at his camp where he decides he doesn't want the bear after all, packs his SUV and leaves.

So what color was the bear that he killed?

8. white

9. What has been done by every male, except for one? Normally does it with many, but can do it by herself. Is world-renowned for her infinite skill and great noise. And gives many great pleasure.

P.S. You'll probably never get this.

10. ## A maths one...

Well here's a maths one (quite easy):

By considering the series,

1 + t + t^2 + t^3 + ... + t^n

sum the series,

1 + 2t + 3t^2 + 4t^3 + ... + nt^(n-1)

for t not = 1, where a^b denotes a raised to the bth power.

Have fun!

11. Good problem!
I think it's

(n * t^(n+1) - (n + 1) * t^n + 1) / (t-1)^2
I even sort of proved it.

12. Originally posted by Nick
Good problem!
I think it's

(n * t^(n+1) - (n + 1) * t^n + 1) / (t-1)^2
I even sort of proved it.
Yeah that's correct, but where's the proof??

13. This is how I found the answer

Code:
```1 + t  + t^2 + t^3 + ...  + t^n
+ t  + t^2 + t^3 + .... + t^n
+ t^2 + t^3 + ...  + t^n
+ t^3 + ...  + t^n
....
+ t^n```
This I proved this was equal to
1 + 2t + 3t^2 + 4t^3 + ... + nt^(n-1)

After that I solved the sums and then used induction

14. Originally posted by Nick
This is how I found the answer

Code:
```1 + t  + t^2 + t^3 + ...  + t^n
+ t  + t^2 + t^3 + .... + t^n
+ t^2 + t^3 + ...  + t^n
+ t^3 + ...  + t^n
....
+ t^n```
This I proved this was equal to
1 + 2t + 3t^2 + 4t^3 + ... + nt^(n-1)

After that I solved the sums and then used induction
I see, well done, but I have a much shorter proof, using 1 + t + t^2 + t^3 + ... + t^n. Can you/anyone else find it?

You'll kick yourselves...

Good Luck!

15. I noticed that derivative
of 1 + t + t^2 + t^3 + ... + t^n
is the 0 + 1 + 2t + 3t^2 +... + nt^(n-1)
I'm sure you could give a prove or solve it some how
using this?

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