Question Discussion & Solution

Given:

2, 10, 18, 54, 162, 486, 1458

Calculation:

The pattern of the number series is:

2 × 3 = 6 ≠ 10

6 × 3 = 18

18 × 3 = 54

54 × 3 = 162

∴ 10 is Wrong Number

7 × 2 – 2 = 12

12 × 3 – 3 = 33

33 × 4 – 4 = 128

128 × 5 – 5 = 635

Calculation:

The series follows the pattern:

⇒ 25 × 8 = 200

⇒ 200 ÷ 5 = 40

⇒ 40 × 8 = 320

⇒ 320 ÷ 5 = 64

⇒ 64 × 8 = 512

∴ The missing number is 320.

The series follows the following pattern:

12 + 11 = 23

23 + 22 = 45

45 + 33 = 78

78 + 44 = 122

122 + 55 = 177

Calculation∶

The series follows the following pattern

11 + 8 = 19 → 2³

19 + 9 = 28 → 3²

28 + 64 = 92 → 4³

92 + 25 = 117 → 5²

117 + 216 = 333 → 6³

∴ The missing term in the series is 117.

Logic: Alternate Cube and Square of consecutive numbers.