Page 5 - Services Selection Board (SSB) Interviews

Part A : Verbal Reasoning

Chapter
Chapter
1 Number Series

Completion

Section Level No. of Questions
Concept Applicator Very Easy 20

Concept Builder Easy 20
Concept Cracker Moderate 30

Concept Deviator Difficult 25

THEORY

In this chapter we will discuss all the questions based on number series. In this type of questions candidate have to
follow a definite pattern throughout the series. The task for the candidate is to follow the pattern and to complete the
given series with the best alternative or to find the wrong term in the series.

DIFFERENT PATTERNS OF NUMBER SERIES

Pattern 1: When the difference between the consecutive numbers is same/ constant or the number series is in arithmetic
progression.
a, a + d, a + 2d, a + 3d, a + 4d, ........, a + (n – 1)d. Where a is first term, d is the common difference
Ex 1: 24, 21, 18, ?, 12, 9.
Where the difference is -3, answer is 15

Pattern 2: Any constant number is added to the difference of the consecutive numbers and form a series.
Ex 2: 2, 4, 8, 14, 22, 30

2 4 8 14 22 32
Next No. is 32 as
2 (2+2) (4+2) (6+2) (8+2)
Ex 3: 3, 4, 6, 9, 13, 18, __, Answer is 24 because 3 4 6 9 13 18 24

Pattern 3: Multiplication or division Pattern 1 2 3 4 5 6
When a series is multiplied or divide by certain constant.
Ex 4: 6174, 882, 126, ?. Answer is 18, the series is divisible by 7.

Ex 5: 1, 2, 3, 6, 9, 18, ?, 54
(a) 18 (b) 27 (c) 36
(d) 81 (e) None of these