Adding up numbers by 6

Question

Hello C-Sharpcorner,
I want to know how to add numbers by 6, starting from #6 
(so, 6->12->18->24.. so forth until 100)

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private void six()
{
Console.WriteLine("the number will go up by 6");
double sixStart =6;

//Below is the nooby method that I came up with
//But I want to know if there is something better than doing this for individual numbers


Console.WriteLine("2nd # ={0}", sixStart + 6);
Console.WriteLine("3rd # ={0}", sixStart +12);

//Are there any formulas to replace this...?

}