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

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

Contents

Problem Description:

``````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%.

## Solution – 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)``````
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