It's easy to convert between hex values and decimal values.
All you need is a calculator that can handle both types.
If you're using Windows, start the calculator that comes with the operating system.
Make sure the view option is set to "scientific".
Enter the decimal value.
Click the Hex field - and watch the calculator convert the number to hex.
Needless to say, you can do it the other way around to calculate decimal values from hex values.
There are a few colors that are so common that they can be defined by their common name.
Jump to the next page to see them...