$.strFiry = function (str) { 
    var lastNum = str.substr(str.length - 1, 1);
    var first15Num = str.substr(0, str.length - 1);
    var newArr = new Array();
    for (var i = first15Num.length - 1; i > -1; i--) { 
        newArr.push(first15Num.substr(i, 1));
    }
    var arrJiShu = new Array();  
    var arrJiShu2 = new Array(); 
    var arrOuShu = new Array();  
    for (var j = 0; j < newArr.length; j++) {
        if ((j + 1) % 2 == 1) { 
            if (parseInt(newArr[j]) * 2 < 9)
                arrJiShu.push(parseInt(newArr[j]) * 2);
            else
                arrJiShu2.push(parseInt(newArr[j]) * 2);
        }
        else 
            arrOuShu.push(newArr[j]);
    }
    var jishu_child1 = new Array(); 
    var jishu_child2 = new Array(); 
    for (var h = 0; h < arrJiShu2.length; h++) {
        jishu_child1.push(parseInt(arrJiShu2[h]) % 10);
        jishu_child2.push(parseInt(arrJiShu2[h]) / 10);
    }
    var sumJiShu = 0;  
    var sumOuShu = 0;  
    var sumJiShuChild1 = 0;  
    var sumJiShuChild2 = 0;  
    var sumTotal = 0;
    for (var m = 0; m < arrJiShu.length; m++) {
        sumJiShu = sumJiShu + parseInt(arrJiShu[m]);
    }

    for (var n = 0; n < arrOuShu.length; n++) {
        sumOuShu = sumOuShu + parseInt(arrOuShu[n]);
    }

    for (var p = 0; p < jishu_child1.length; p++) {
        sumJiShuChild1 = sumJiShuChild1 + parseInt(jishu_child1[p]);
        sumJiShuChild2 = sumJiShuChild2 + parseInt(jishu_child2[p]);
    } 
    sumTotal = parseInt(sumJiShu) + parseInt(sumOuShu) + parseInt(sumJiShuChild1) + parseInt(sumJiShuChild2);
         var k = parseInt(sumTotal) % 10 == 0 ? 10 : parseInt(sumTotal) % 10;
    var luhm = 10 - k;

    if (lastNum == luhm && lastNum.length != 0) {
        return true;
    }
    else { 
        return false;
    }
}
