- A reference guide and manual in Russian for Heroes 3.

Increasing mana by 25% (for basic intelligence) will be no trouble

If the mana is indeed increasing, then the formula is incorrect.

but increasing knowledge by 25% is problematic because fractions appear...

So what if there are fractions? What prevents multiplying a fractional number by 10 (to calculate mana) and then rounding it to the nearest whole number?

For example, a hero has 10 knowledge and receives basic intelligence.
Calculating by mana: 10 knowledge * 10 mana * 1.25 (basic intelligence coefficient) = 125 mana
Calculating by knowledge: 10 knowledge * 1.25 * 10 mana = 125 mana
Looking at these formulas, it is clear that they are the same; only the multipliers change places.