Try this. This seems to be working,.
int number = 5;
for (int i = 0; i < number; ++i)
{
for (int j = 0; j <= i; ++j)
{
Console.Write("*");
}
if (i != number - 1)
{
Console.Write(" ");
}
else
{
Console.Write(" * ");
}
for (int j = 0; j <= i; ++j)
{
Console.Write("*");
}
Console.WriteLine();
}