Missing Terms in Series – Logical Reasoning – MBA CUET PG – Notes & Practice Questions

Alphabetical series are combinations of alphabets connected to each other with a rule.
The rule may involve increment, decrement, opposite alphabets, or any other mathematical operation.

There are two types of alphabetical series:

1. Alphabetical word–based series

2. String–based series

(a) Alphabetical Word–Based Series

These series use alphabetical words that are connected to each other through a pattern.
The pattern may apply to the first letter, middle letter, or last letter.

Example:

GIJ, LNO, ___, VXY, ACD

Here, the first letter increases by +5 place value.
Middle and last letters also increase by +5.

(b) String-Based Alphabetical Series

In a string-based series, any type of string pattern is used, and there is a blank to fill.
You must find the rule and fill the blank accordingly.

The rule may involve:

• Repeating the string pattern
• Adding or removing letters
• Shifting letters

Examples

(a)
bc abd / bc abd / bc abd / bc
It is a repeating pattern of “bc abd”.

(b)
abc bcd cde def

Letters are added and removed based on a pattern:
First letter is deleted and a new letter is added after the 3rd letter.

Numerical Series

A numerical series is based on numbers and follows a pattern such as:

• Increment
• Decrement
• Square
• Cube
• Prime number
• Any mathematical operation

Examples

(a)
71, 59, 48, 38, 29, ___

The differences are –12, –11, –10, –9, –8
Next difference will be –7
So the next term is 21

(b)
5, 9, 18, 34, 59, ___

These follow increasing increments:
2², 3², 4², 5², 6² …
Next increment is 7² = 49
So the next term is 95

Points to Remember

(A) Alphabetical Series

• Letters are always related to their place value and opposites.

• A–Z sequence works normally but can also be reversed.

(B) Numerical Series

The number sequence may involve repeating rules such as:

1. Increment or decrement of natural numbers

2. Tables of any number

3. Increment/decrement in:

   • Prime numbers

   • Odd numbers

   • Even numbers

4. If the difference between terms is large, the rule may involve:

   • Squares

   • Cubes

   • Multiplication

   • Division

5. If results include decimals:

   • It may be a decimal sequence

   • Mathematical operation

   • Series based on division

(C) String-Based Series

• Always look for a repeated pattern in the strings.

• Fill the blank according to the repeating sequence of the combination.

Practice Questions

1. Which number will replace the question mark? in the below mentioned series; (CUET PG 2024)

13, 37, 77, 157, 317,?

(a) 637

(b) 649

(c) 683

(d) 634

2. Which number will come next in the series: 3, 10, 33, 104, 319,? (CUET PG 2024)

(a) 960

(b) 966

(c) 969

(d) 1000

3. Which number will come next in the series: 4, 10, 19, 40, 79, 160, ? (CUET PG 2024)

(a) 310

(b) 320

(c) 315

(d) 319

4. 2 1 9 5 4 6 8 4 1 6 9 8 4 1 3

How many odd number are present in the given series which is preceded by a perfect square and having followed by a odd number.

(a) 2

(b) 3

(c) 4

(d) 1

5. 158, 113, 78, 53, 28, ?

(a) 13

(b) 12

(c) 11

(d) 14