How many Canadian Dollars are equivalent to one Euro, the Europian currency?

You have twelve coins, one of which is a counterfeit. You have a balance, but it’s not the kind of balance that you can measure things on, it only has two ends with a fulcrum
in the middle, in other words, it only tells you which end is heavier. You can use the scale three times to weigh things. You know that the counterfeit coin is either heavier or lighter than a normal coin, but you don’t know which. How do you find the counterfeit coin?
This is part of my homework, please be serious.

I found this strangely marked coin in my change and I’m wondering if this was a mint error or if someone has defaced this coin… here is an image of it:

http://i38.photobucket.com/albums/e115/yarcofin/coinerror.jpg

On the back there is also a little bit of a curved clip on the core, but it doesn’t seem to be visible in this picture.

I’ve already checked this website http://members.allstream.net/~err/ but it doesn’t seem to be listed as a known error.
I know what a Toonie is, I’m Canadian…. I mean the perfectly round giant scratch on the front side.

okay,
the coin on the very very bottom,
who knows how much its worth?

http://www.teachersatrisk.com/wp-content/uploads/2009/01/canadian-coins.jpg

I live in Alberta and am contemplating my career path. The one I am looking at starts at 000 a year. I am currently single but would someday like my own house, a horse, a car. What is the outlook? Lol
Please note when answering: Canadian currency is not the same as american. 000 is about ,000 American.

Someone told me it was a rare coin, but I can’t find any information on it anywhere. It’s in good condition.

Suppose You have 5 stacks with 20 supposedly gold coins in each stack. Each authentic gold coin weighs 10 grams, but two of the stacks are composed of only counterfeit coins weighing 11 grams each. You are given a scale the weighs grams. Figure out a way to determine the counterfeit stacks in one weighing using the scale.