What is the color of a given hex value, between 0 and F, for example, #707070 ?

Download and install Paint.NET at http://www.filehippo.com/download_paint.net/.

Open Paint.NET.

Make sure the Colors frame is opened. If not, click on Menu > Window > Colors (F8).

On the Colors frame, click on More>> button.

Key in the Hex value, key in 707070 as an example.

To know the color, see the square box at top left corner. That's all for now.