return arr.reduce(function(x,y){
        return x*y;
    });

var arr=s.split('').map(function(x){return x*1;});
return arr.reduce(function(x,y){
    return x*10+y;
});

return arr.map(function(item){
    return item[0].toUpperCase()+item.substring(1).toLowerCase();
});

r = arr.map(function(x){return parseInt(x);});