If there is a discrete set, example {1,2,3,14,15,16,21,22} how to write this mathematically?
A mathematical equations should satisfy if sets varies too. Kindly help me out, thanks in advance.
In this set 1-3 is of continuous, 14-16 is continuous and final is 21-22. It forms three ranges can it be written in expression with some notations.
For example if 1-3 is alone present we can write it as simple as 1:3 but here there are several ranges that exists. How to give notation for this scenario?
What you already have is fine, and for small sets would be entirely normal. You can also, in this case, write it as a union of integer intervals. We can write $[m\ldots n]$ to denote $[m,n]\cap {\mathbb Z}$, i.e it is the set of all numbers between $n$ and $m$ inclusive that are integers. So as an example, $[2\ldots5] = \{2,3,4,5 \}$. Then your set becomes $$ [1\ldots 3] \cup [14\ldots 16] \cup [21\dots 22]$$