There are two ways of naming chemical thingies - IUPAC or trivial names. IUPAC names are systematic and the same for everything that might have one carbon. The trivial names are what these used to be called, but aren't any more. (Please click here for the wikipedia post on the topic. I found it interesting...) You'll recognize some of these, I'm sure...
1 carbon - IUPAC: meth-, trivial: form-
As in methane or formic acid.
2 carbons - IUPAC: eth-, trivial: ace-
As in ethane or acetic acid.
3 carbons - IUPAC: prop, trivial: (not used)
Propane or propylene glycol (meaning there are 3 carbons in propylene glycol). Also something like isopropyl alcohol. (The "iso" part means it is an isomer of propyl alcohol.)
4 carbons - IUPAC: but-, trivial: (not used)
As in butylene glycol. Or butyric acid, the fatty acid found in butter.
As a note, when you see something like "butylene glycol" the "-lene" part of the word means it is an alkene, a chain with at least one double bond between carbons, and it is unsaturated. It's an easy way to remember the difference between squalane and squalene. The squalene has a double bond somewhere on the chain, which means it can be broken and rancidity can happen. So the squalane is saturated and will not go rancid as fast as the squalene.
16 carbons - IUPAC: hexadec-, trivial: cet-
As in cetyl alcohol, cetearyl alcohol, and cetrimonium bromide or cetrimonium chloride. So you know there are 16 carbons on the chain.
18 carbons - IUPAC: octadec-, trivial: stear-
As in stearic acid or stearalkonium chloride. You know there are 18 carbons in these ingredients.
22 carbons - IUPAC: docos, trivial: behe-
As in behetrimonium sulphate. The behe means there are 22 carbons.
No, there isn't a test, but it is useful information for upcoming posts on cationic quaternary compounds!