First person to give me the correct answer, wins a copy of Brutal Legend!!

You have 13 weights and a balance
The 13 weights weigh 1kg, 2kg, 3,g etc, up to 13kg in WHOLE NUMBERS.

This is a balance for those of you who don't know:
http://www.berkeleyrunningcompany.com/portals/3/Images/balance2.gif

Note: It does not matter what type of unit you use, it does not affect the riddle.
This is only is only an example.

Now heres the Riddle: Using only 3 weights,can you create every single weight from 1kg to 13kg on a balance?

For example: using the weights 1,2 and 3

1kg onone side and nothing on the other side can create a weight of 1kg on a balance,
2kg on one side and nothing on the other side can create a weight of 2kg on a balance,
3kg on one side and nothing on the other side can create a weight of 3kg on a balance,
1kg + 2kg can also create a weight of 3kg on a balance on one side,
2kg on one side and 1kg on the other side can create a weight equal to 1kg on a balance since 2 - 1 = 1,
1kg + 3kg can create a weight of 4kg on a balance.
2kg + 3kg can create a weight of 5kg on a balance.
1kg + 2kg + 3kg can create a weight of 6kg on a balance.
But this is as far as they can go, so therefore, it is impossible for it to be this combination.

So once again, can you create every single weight from 1kg to 13kg on a balance using ONLY 3 weights?
Remember: You cannot use the same weight twice as you only have a quantity of one weight each and the type of units do not affect the outcome.
All weights are in whole numbers, so there is no halving of weights.

Post your answer in the link below and don't forget to join the group. I always do random giveaways like these.
http://steamcommunity.com/groups/Wisamsgiveaways#announcements/detail/1801733269020783775

This is also a good way for you to win games if you consider yourself unlucky ;)

Good Luck Everyone!!!!!