byStarTW says to YSITD /* Gregory–Leibniz series π = 4/1 - 4/3 + 4/5 - 4/7 + 4/9 - 4/11 .... */ var pi = 0; var i = 1; while(true){ pi = pi + ( 4 / i ) - ( 4 / ( i + 2 ) ); i += 4; console.log(pi); }