Concept 1:

Addition and Subtraction method.

Eg: 12, 15, 18, 21, 24, ? (Addition)

Eg: 85, 80, 75, 70, 65, ? (Subtraction)

Concept 2:

Multiplication and Division method.

Eg: 2, 2, 4, 12, 48, 240, ? (Multiplication)

Eg: 360, 72, 18, 6, 3, ? (Division)

Concept 3:

Prime number and Composite number series.

Eg: 2, 3, 5, 7, 11, 13, ? (All are consecutive prime numbers)

Eg: 4, 6, 8, 9, 10, 12, ? (All are consecutive composite numbers)

Concept 4:

Squares & Cubes method.

Eg: 25, 36, 49, 64, 81, ? (Consecutive squares)

Eg: 1, 8, 27, 81, 125, ? (Consecutive cubes)

Eg: 2, 5, 10, 17, 26, ? (n² + 1 Logic)

Eg: 0, 7, 26, 63, 124, ? (n³ – 1 Logic) etc.

Concept 5:

Triangular & Pythagoras triplet series.

Eg: 7, 10, 15, 24, 39, ? (Triangular Series)

Eg: 3, 4, 5, 5, 12, 13, 7, 24, 25, 8, 15, ? (Pythagoras Triplet)

Concept 6:

Arithmetic & Geometric progression series.

Eg: In the series 3, 9, 15, 21, . . . . . . , what will be the 21^st term? (Arithmetic Progression)

Eg: In the series 2, 6, 18, 54, . . . . . . . , what will be the 8^th term? (Geometric Progression)

Concept 7:

Sum of the digits series.

Eg: 13, 17, 25, 32, 35, 43, 50, ? (Sum of the digits series)

Concept 8:

Wrong number series.

Eg: Find the wrong number in the following number series.

26, 27, 34, 58, 106, 186, 306

Find the missing term from the following number series:

68, 86, 59, 104, 41, ?

a) 138              b) 132              c) 140              d) 148              e) 130

Solution:

The Pattern of the series are as follows-

⇒ 68 + (9 x 2) = 86

⇒ 86 - (9 x 3) = 59

⇒ 59 + (9 x 5) = 104

⇒ 104 - (9 x 7) = 41

⇒ 41 + (9 x 11) = 140

Answer: c

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