I need function that calculates amount of games required to reach certain rating with defined winrate

Question

function ChangePts(pts) {
  this.pts = pts;
  
  this.win = function() {
    console.log(this.pts + 30)
    return this.pts += 30
  }

  this.lose = function() {
    console.log(this.pts - 30)
    return this.pts -= 30;
  }

};
           

I made it to calculate how many games you need to lose, to get certain ratingw with while loop. This implies that win% is 0%, how do I calculate amount of games if we declare starting pts for example 5000, how many games it takes to get to 1000 pts if your winrate is 27% P.S.: For this case I need only negative amount of win%.

Answer 1

You can just calculate it like this (variables should be explanation enough). There is no real coding necessary for it, just math calculations

const winRate = 0.27
const loseRate = 1-winRate
const pointsWin = 30
const pointsLose = 30
const startingPoints = 5000
const targetPoints = 1000

const pointsGainedOnAverage = pointsWin*winRate - pointsLose*loseRate
const pointsDistance = targetPoints - startingPoints
const games = pointsDistance / pointsGainedOnAverage
console.log('games', games)