JavaScript计算 a+aa+aaa...... a是数字

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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>

        /**
         *  a+aa+aaa+...的和  a是数字
         * @param num 指定循环的数字
         * @param size  循环的次数 例如:2,22=20+2,222=200+22....
         */

        function t4(a,count){
            var sum =0, b=0

            for(var i=1;i<count;i++){
                b = b + a
                sum = sum+b
                a = a*10
            }
            return sum
        }


        console.log(t4(2,4))


    </script>
    
</body>
</html>

<!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>

        /**
         *  a+aa+aaa+...的和  a是数字
         * @param num 指定循环的数字
         * @param size  循环的次数 例如:2,22=20+2,222=200+22....
         */

        function t4(a,count){
            var sum =0, b=0

            for(var i=1;i<count;i++){
                b = b + a
                sum = sum+b
                a = a*10
            }
            return sum
        }


        console.log(t4(2,4))


    </script>
    
</body>
</html>

原文地址：https://www.cnblogs.com/qiuyehaha/p/12935218.html