[dreamcompiler]

Let's say I hire a plumber because of his plumbing expertise and he bills me $35 and I pay him with a $50 bill and he gives me back $10 in change. He insists he's right about this.

I am now completely justified in worrying about whether the pipes he just installed were actually made of butter.

[xandrius]

Really? Is that easy? Happens quite often to really believe something and be wrong. Maybe you both are right and the $5 bill is on the floor?