新gre数学重要考点：Combinations of Choices

　　2014新gre考试实施以来，不仅对写作部分茫然不知所措，就连我们所擅长的数学也甚是担忧，相信这其中的原因还是由于考生在新gre数学复习时没有把基础打牢。如果新版gre数学基本考点都没有复习到，如何能拿到分数呢?所以说，想要新版gre数学考好，复习的时候一定要把基本概念和重要考点都弄扎实。

　　Combinations of Choices

　　If there are n choices for one type and m choices for second type, then number of combinations for both types is the product of choices:nm.

　　Example:

　　If there are 3 kinds of breads to choose from and 4 kinds of meats, then we can make 34=12 different sandwiches.

　　If an alphabet has 26 letters, then the number of possible 2 letter word is 2626=676.All of them may not be vaild words.

　　Remember:

　　Do not add the choices to get the total combinations.

　　The product rule can be applied to more than two types of choices: if there are 3 kinds of breads, 4 kinds of meats, and 6 kinds of cheeses, then we can make 346=72 different sandwiches.

　　由于美国数学基础教育的难度增加导致数学考试越来越难，但新gre数学复习考点都是高中时候学到的知识点，考生不要过于紧张，把基本概念弄明白，再记住一些新版gre数学必备的词汇，那么相信新版gre数学应该没有问题。