Question

Help?

Answer 1

It takes 2 cards to build 1 floor of a card house.
It takes 7 cards to build 2 floors of a card house.
It takes 15 cards to build 3 floors of a card house.

How many cards does it take to build a 10-story house?

Answer 2

well you need to find a general term for the number of cards needed
actually i don't know a scientific we to reach this general term ( i don't know if there is such a way :P) but by trying i found that :
3^0 + 1*2 = 2
3^1 + 2*2 = 7
3^2 + 3*2 = 15

so the general term may be 3^(n-1) + n*2 where n is the number of floors

Answer 3

http://thumbs.dreamstime.com/z/card-house-5404051.jpg

So I Googled what a card house actually looks like. It has these triangular structures stacked up on each other, and each triangular structure has 3 cards on it.

Answer 4

I just did...

Answer 5

I got the answer tho. It's 155, right?

Answer 6

Wow... you got it.

Answer 7

Thanks! :3

Answer 8

Cool. How did you get it?

Answer 9

My friend ;D

Answer 10

...you cheater.

Answer 11

LOL no! She just showed me how to solve it and i got the answer myself ;P

Answer 12

Good. The general formula I got is \[\dfrac{3n(n+1)/2 - n}\]

Answer 13

And yeah!

Answer 14

So do I. :3

Answer 15

Really? You judge by SS?