Random number showing in every few seconds Wordpress Shortcode

I need help to create shortcode for my wordpress site..

What I would like to add is: “(random number) calories”

And the random number shows in range of 1300 - 5000 and it changes every 3-4 seconds.

I think I have to add code in functions.php in Wordpress theme to create shortcode..

Could anyone help to create code that I can add in fundctions.php to add shortcode?