string first = "Hello";
string second = "World";
string result = string.Format("{0} {1}!", first, second);
Console.WriteLine(result); // Hello World!

decimal price = 123.45m;
int discount = 50;
Console.WriteLine($"Price: {price:C} (Save {discount:C})"); // Price: $123.45 (Save $50.00)

decimal measurement = 123456.78912m;
Console.WriteLine($"Measurement: {measurement:N} units"); // Measurement: 123,456.79 units
Console.WriteLine($"Measurement: {measurement:N4} units"); // Measurement: 123,456.7891 units

decimal tax = .36785m;
Console.WriteLine($"Tax rate: {tax:P2}"); // Tax rate: 36.79%

string input = "Pad this";
Console.WriteLine(input.PadLeft(12)); // " 	Pad this"
Console.WriteLine(input.PadLeft(12, '*')); // "****Pad this"
Console.WriteLine(input.PadRight(12, '*')); // "Pad this****"