NTSE MAT - Number Series

July 5, 2011


Number Series is one of the most important topics in NTSE. This involves picking an odd one out, finding analogies, number series or finding the missing number. The questions do not involve heavy maths only great observation. So with great practice you can pick up patterns fast and without solving.

Described below are some important patterns seen among questions from this topic in NTSE. Basic number series can be formed by applying some operation on the previous number or applying operations on a series existing naturally like whole numbers, even or odd numbers, natural numbers etc.

These are mentioned in the increasing order of their importance.

Mathematical Operations

This is the most important pattern in the number series questions. The most favourite among these are square and cubes. Few examples are Squares and Cubes, addition, subtraction, multiplication

How to identify the pattern
1. The series based on squares and cubes must be increasing at a very high rate.
2. Many of the questions in multiplication follows a rule n x (last number) +- n

Examples
4, 9, 24, 69, __
Here n = 3 so missing number will be 204

Jumping in Natural Order

You can count this one as a part of Mathematical Operations but I decided to keep it separate. Numbers appear in the natural order but some numbers are skipped in between.

How to identify the pattern
The sequence in the series must be following some pattern like +2, +3 or some other higher number.

Examples
2, 7, 12, 17, __
Missing number will be 22 as we are jumping 5 numbers in between two numbers in the series

Jumping in Reverse Order

This is same as above only skipping happens in reverse order.

How to identify the pattern
The sequence in the series must be following some pattern like -2, -3 or some other higher number.

Examples
25, 22, 19, 16, __
Missing number will be 13 as we are jumping 3 numbers in reverse order between two numbers

Combination of Two Series / Alternating Series

Here two series are mixed up into one. This is the one when you cannot find a straight pattern.

How to identify the pattern
Generally these series as a whole will not be following any sequence but the alternate numbers will be following a sequence which can be formed by using any of the patterns above.

Examples
3, 7, 6, 5, 9, 3, 12, __

Here there are two series, in one series there are multiples of 3 and in other the numbers are jumping in reverse order by a gap of 2, so missing number will be 1

Time to Practice


Practice related questions on SimplyLearnt.com now:
Classification: http://www.simplylearnt.com/practice/questions/summer/Classification
Series (Verbal): http://www.simplylearnt.com/practice/questions/summer/Series--Verbal

Analogies (Verbal): http://www.simplylearnt.com/practice/questions/summer/Analogy--Verbal-

Happy Practice