We will use scientific notation extensively - namely exponentials. The exponent indicates the number of places to the left (positive exponent) or right (negative exponent), of the units place the decimal point occurs. Another way to look at it is that the exponent for a power of ten indicates how many zeros would come before a 1 if you wrote the number out. Thus 10^6 (one million) is written as 1,000,000 (or 6 zeros). A negative power of ten means you divide by that number, eg. 10^(-6) is one millionth. If you multiply two powers of ten together, you add the exponents. If you divide them, you subtract the exponents, eg. 10^6/10^2=10^(6-2)=10^4.

Another concept that is useful is the precision of a calculation. If you multiply several numbers together, the answer shouldn't have more than one more decimal place than the number being used that had the LEAST number of places (or precision). For example, 1.2x10^4 times 3.563x10^2 is 4.3x10^6, not (as my calculator says) 4.2756x10^6. In any case, in this class we are almost never interested in numbers to better than 2 decimal places (astronomy is a rather approximate science, for the most part).

For a much more detailed and informative description of how to handle numbers in this class, use our Numerical Resource Guide.