var paper = Raphael(0, 0, 600, 600);
// Creates circle at x = 50, y = 40, with radius 10
var n=0;
var m=0;
document.onkeypress=function(){
for(var i=0;i<1;i++)
{
var x = Math.random()*400+100;
var y = Math.random()*400+100;
var circle = paper.circle(x, y, 4);
//circle.attr("fill", "#f00");
var d = Math.sqrt((x-300)*(x-300)+(y-300)*(y-300));
n++;
if(d<200)
{
m++
}
console.log(m,n,m/n*4);
}
var circle = paper.circle(300,300,200);
}
<canvas id="canvas"></canvas>