Check out below code, it will give you 30 random 5 digits numbers.
List<int> numbers = new List<int>();
for (; numbers.Count < 30; )
{
int i = new Random().Next(10000, 99999);
if (numbers.Contains(i)) continue;
numbers.Add(i);
}
if condition is been mentioned in the code, so that numbers should not contain duplicate numbers. You can change the for loop condition depend how many numbers you want.