## NUMBER AND LETTER SERIES

Number
and Letter Series form an important part of the Reasoning section in various
competitive examinations. There are two or three broad categories of questions
that appear in various exams from this particular chapter.

In
the first category of questions, a series of numbers/ letters is given with one
number/letter (or two numbers/letters) missing, represented by a blank or a
question mark. The given series of numbers/letters will be such that each one
follows its predecessor in a certain way, i.e., according to a definite
pattern. Students are required to find out the way in which the series is
formed and hence work out the missing number/ numbers or letter/letters to
complete the series. For the purpose of our discussion, we will refer to this
category of questions as Number Series or Letter Series Type I questions. Under
Type I questions, there are a large variety of patterns that are possible and
the student requires a proper understanding of various patterns to be able to
do well in these types of questions. .

### Number Series:

For
better understanding, we will classify this into the following broad
categories. .

- Difference
series
- Product
series
- Squares/Cubes
series
- Miscellaneous
series
- Combination
series