Quote Originally Posted by avenger View Post
if i upgrade my stadium cost 200m i get 157K seats... if i upgrade only seats max lvl 18K cost 150m i will get 151K stadium
Nope.
EACH upgrade adds 6000 seats, in your case.

If you do them in order:
Small adds 6k for 6k total
Medium adds another 6k for 12k total
Large Adds another 6k for 18k total
Then you have one additional upgrade of 6k to reach 24k total bringing you to 157k and the same as a stadium upgrade.