**Series Completion Reasoning Material for All Competitive Exams | PDF Download**

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This section deals with questions in which series of numbers or letters are given. The term follows a certain pattern throughout. The candidate is required to recognise this pattern either to complete the given series with the most suitable alternative or to find the wrong term in the series.

**Number Series**

**Example-1**– Which number would replace the question mark (?) in the series 2, 7, 14, 23, ?, 47

(1) 28 (2) 34 (3) 31 (4) 38 (5) None

**Ans:** The given sequence is +5, +7, +9,——- , ie. 2+ 5 = 7, 7 + 7 = 14, 14 + 9 = 23

Missing Number = 23 + 11 = 34.

**Example -2**– Find the wrong number in the series- 7, 28, 63, 124, 215, 342

(1) 7 (2) 28 (3) 124 (4) 215 (5) None

**Ans**:The correct sequence is 2^{3}– 1, 3^{3} – 1, 4^{3} – 1, …etc.

Here 28 is wrong; so the answer is (2)

**Alaphabet Series**

Alphabet series consists of letters of the alphabet placed in a specific pattern. If you keep in your mind the order of the letters with their respective numbers it will help you answer the questions quickly.

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 |

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |

26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 |

**Example**. What will be the next term in BKS, DJT, FIU, HHV, ?

(1) IJX (2) IGX (3) JGW (4) IGU(5) JGU

Ans: (3). In each term, the first letter is moved two steps forward, the second letter one step backward and the third letter one step forward to obtain the corresponding letter of the next term. So, the missing term is JGW.

**Letter Series**

This type of question usually consists of a series of small letters which follow a certain pattern. However some letters are missing from the series. These missing letters are then given in a proper sequence as one of the alternatives. The candidate is required to choose this alternative as the answer.

**Example**. aab – aaa – bba –

(1) baa (2) abb (3) bab (4) aab(5) bbb

1.The first blank space should be filled in by ‘b’ so that we have two a’s followed by two b’s.

2.The second blank space should be filled in either by ‘a’. So that we have four a’s followed by two b’s, or by ‘b’. So that we have three a’s followed by three b’s.

3.The last space must be filled in by ‘a’.

4.Thus we have two possible answers – ‘baa’ and ‘bba’.

5.But only ‘baa’ appears in the alternatives. So the answer is (1).

6.In case we had both the possible answers in the alternatives, we should choose the one that forms a more prominent pattern, which is aabb/aaabbb/aa. and our answer would have been ‘bba’.

Series Completion Reasoning Material for All Competitive Exams (Download Here)

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