How to calculate..

The question is a little unclear. I am answering it according to what I have understood for it.

In general, in a compound see the central atom. Draw its lewis structure.Check its bonding and then you can check whether is there any unpaired electron in it or not.

For example:

In NO₂, the structure is:

See here N has 5 valence electrons, with 2 electrons it forms a double bond, 2 electrons it donates for sharing as a coordinate bond. So, it is left one electron. So, it is an odd electron speices.

If you want to ask for any other type do ask again.