<code></code>
public static double Calculate(string userInput)
{
var tokens = userInput.Split(' ');
var sum = decimal.Parse(tokens[0]);
var percents = decimal.Parse(tokens[1]) / 100m / 12m;
var months = int.Parse(tokens[2]);
return (double) CalculateInternal(sum, percents, months);
}
private static decimal CalculateInternal(decimal sum, decimal percents, int months) =>
months == 0
? sum
: CalculateInternal(sum * percents + sum, percents, months - 1);