perf(xp): simplify function LevelXP

README.md

@@ -15,7 +15,7 @@ Functions:
 message (number of different rune)
 - $xp-vocal(x)=0.01 x^{1.3}+1$ where $x$ is the time spent in vocal (in second)
 - $level(x)=0.2 \sqrt{x}$ where $x$ is the xp
-- $level^{-1}(x)=(5x)^2$ where $x$ is the level
+- $level^{-1}(x)=25x^2$ where $x$ is the level
 
 ## Installation
 

exp/functions.go

@@ -42,7 +42,7 @@ func Level(xp uint) uint {
 // See Level to get the level with the given XP.
 func LevelXP(level uint) uint {
 	return uint(math.Floor(
-		math.Pow(float64(5*level), 2),
+		25 * math.Pow(float64(level), 2),
 	))
 }