lovecoding
/
Web1020


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        function foo(n){
            var res = 0;
            for(var i=1;i<=n;i++){
                res += Math.pow(-1,i-1)*(1/(2*i-1));
            }
            res *= 4;
            return res;
        }
        console.log(foo(100));
        console.log(foo(500));
        
        
        
    </script>
</body>
</html>