Adsense help please?

i just want to know if is it true that if i have adsense on my site and lets say i have a skyscraper add thin with like 4 adds .
is it true that the add at the top is worth more then the others?
if so than it would be better to just put a little square at the top with one add, because then people would aways click on the high paying add. correct ?

The ad at the top make more money that is true.
By having more ads on the page you will make more money by having more of an option.