If you are trying to get your electrical licensing in Missouri you should probably know that there isn't a single state regulation regarding electrical licenses.
However, (there is always a however) some local governments on a city or county level requires certification or licensing for work to be done by an electrician.
To get your electrical licensing in Missouri, check first with the county government in the area in which you are working to find out the local requirements.
There are some references online about where to look for that information, I have posted some of them below for you.
If you want to prepare for your electrical exam, click here to download a free e-book that will help you study.
Best of luck!