I've created two sectionwise defined functions for these calculations. Probably someone came up with that before me but I havent found it in the forum so I will post them here

They may not be very useful without a calculator, but a computer should handle them well^^

LVL is the Level you want to enhance your unit to.

EXP(LVL) is the experience points needed to enhance your unit from to LVL

LVL^2 means LVL*LVL.

EXP(LVL)=25LVL^2+25LVL-50

for 0<LVL<=22

EXP(LVL)=30LVL^2-190LVL+2260

for 22<LVL<=44

EXP(LVL)=35LVL^2-605LVL+10870

for 44<LVL<=66

EXP(LVL)=50LVL^2-2450LVL+67600

for 66<LVL<=88

EXP(LVL)=75LVL^2-6525LVL+233650

for 88<LVL<=102

EXP(LVL)=162.5LVL^2-24112.5LVL+1117400

for 102<LVL<=120

With this, the Experience needed to go from level a to level b is simply EXP(b)-EXP(a)

Of course this can be turned the other way around:

EXP is the amount of experience you want to feed to your unit.

LVL(EXP) is the level you can reach with EXP experience.

(number)^0.5 is the square root of the number .

LVL(EXP)=-0.5+ (EXP/25+2.25)^0.5

for 0<=EXP<=12600

LVL(EXP)=19/6 + (EXP/30-2351/36)^0.5

for 12600<EXP<=47200

LVL(EXP)=121/14+ (EXP/35-235.872449)^0.5

for 47200<EXP<=107900

LVL(EXP)=24.5+ (EXP/50-751.75)^0.5

for 107900<EXP<=202900

LVL(EXP)=43.5+(EXP/75-14677/12)^0.5

for 202900<EXP<=348575

LVL(EXP)=1929/26+(EXP/162.5-1371.809172)^0.5

for 348575<EXP<=563900

If your level a unit gets e experience it reaches level LVL(EXP(a)+e).

Have fun trying them out