using System;

using System.IO;

using System.Text.Json;

using System.Text;

​

public class Program

{

    public static void Main()

    {

        var options = new JsonWriterOptions

        {

            Indented = true

        };

​

        using var stream = new MemoryStream();

        using var writer = new Utf8JsonWriter(stream, options);

        decimal x = 42;

​

        writer.WriteStartObject();

        writer.WriteNumber("temp", x);

        writer.WriteEndObject();

        writer.Flush();

​

        string json = Encoding.UTF8.GetString(stream.ToArray());

        Console.WriteLine(json);

    }

}