Overall most people tend to learn better this way rather than trying to learn all Excel formulas at the same time as this can be very confusing. Most of us tend to learn in smaller packages of information and you should look for a course of instruction that will allow you to do this. As you are learning to use Excel you should of course start by learning to use the formulas that you are actually using or are likely to have need of in the immediate future.
This may sound a little unfair. After all, a standard Microsoft installation would include something called Equation Editor. Suffice to say, it wasn‘t advertised in the promotional videos. Software like Matlab was considered vastly superior and had the added advantage that you could analyze the equations as well. Anyway, the good news is that Microsoft has taken a big step forwards with Office 2010 and it‘s now possible to correctly display formulas in a pretty painless fashion. In Excel 2010, you should select the Insert ribbon, and click Equation. This creates a textbox and brings up a whole new ribbon with options for inserting equations. As well as providing easy access to the main Greek symbols, Microsoft have provided quick access to a number of simple functions, such as fractions and exponentials.