your final guess war right Jim.. I know for a fact that the UP works on a Linear Series of a common Difference of 15000 Naq.. The equation is constant.. so if you hadta type in 100 and click 10 times, or type in 1000 and click once.. will cost you the same
The
MATH:
The Equation for The Sum of a Linear series is Sn=n/2((2a+(n-1)d). Using that if we wantd a 300 UP we'd enter 100 into the Box thing. Substituting everything into the Equation u'd get a total sum payment of 74'750'000.
However if i wanted a 300 UP and entered increments of 50 instead of 100 as in the first instant this is what would happen:
First 50(150 UP) Total payment = 18'625'000
Second 50 (300 UP) Total Payment = 56'125'000
Add the two and you get 74'750'000 Easy as pie! (no pun intended)
I'm pretty sure the same applies to MS and Planets.. However don't ask me about the Ascension power up levels.. but I'm pretty sure those are a Geometric Series
