Pure Mathematics to Actuarial Science. I did my undergraduate in pure mathematics and recently after a three year break I decided to get a master's degree in Actuarial Science. I am in the second week of classes and I feel completely lost. Thus, brings me to the question Can a pure mathematician survive a master's degree in Actuarial Science? and Also what are some elementary course that are missing from a pure mathematics degree that would be needed to get a master's degree in Actuarial Science. For the first time in my life I feel completely dumb. 
 A: I recently graduated with an undergraduate degree in Actuarial Mathematics. I took courses in both the pure and actuarial math branches.
Actuarial Specific Subjects you may be interested in:
Probability + Stats - Basic probability theory is necessary. Any additional knowledge of stats is highly recommended.
Theory of Interest - Learn about time value of money and how it applies to all classes of standard annuities.
Life Contingencies - Blend theory of interest with probability to start building actuarial models dependent on both time and likelihood.
Risk Theory - Learn about various models of risk as well as how to manipulate several 'standard' risk theory models.
Often, finance courses and Mathematical Finance courses (stock options and Black-Scholes) are recommended at the graduate level as well.
ACTEX Publications offers some pretty good course material here. Filled with practice problems and they also have study manuals (which can be kinda pricey :/)
I've personally used their Theory of Interest Text, Life Contingencies, and Risk Theory books and 'enjoyed' them.
Hope that helps
A: To add to jameselmore's answer, you also need some background in the following courses:
Survival Models - Survival analysis attempts to answer questions such as: what is the proportion of a population which will survive past a certain time? Of those that survive, at what rate will they die or fail? Can multiple causes of death or failure be taken into account? How do particular circumstances or characteristics increase or decrease the probability of survival?
Graduation - Smoothing of time series to fit curves to data, such as cubic splines.
I would also suggest the actuarial exam reviewers by Finan and Guo.
