Number Series Rules

Series is an important chapter from banking examination point of view. Following are some of the important rules or order on which the number series can be made :-

Pure Series

Difference Series 

Ratio Series 

Mixed Series

Geometric Series

Two Tier Arithmetic Series

Other Types

  1. Pure Series

In this type of number series, the number itself obeys certain order so that the character of the series can be found out.

The number itself may be.

Perfect Square

Example :

121, 144, 169, 225 ?

Answer – 256

Perfect Cube

Example :

6859, 5832, 4913, 4096, 3375, ?

Answer – 2744

  1. Difference Series

Example :

1348, 1338, 1318, 1288, 1248, ?

Answer – 1198

  1. Ratio Series

Example :

336, 168, 84, 42, 21, ?

Answer – 10.5

  1. Mixed Series

Example :

222, 441, 1321, 2639, 7915, ?

Answer – 15827

  1. Geometric Series

Example 1. 5, 35, 245, 1715, ?

Ans. 12005

Examples 2. 43923,3993, 363, 33, ?

Ans. 3

  1. Two-tier Arithmetic Series
  2. Other Type

To find the odd number from the number series. In this type of series the above rules are also followed.

Some Examples ;

2, 3, 7, 22, 89, 440, 2677, 18740

Solution : ×1+1, ×2+1, ×3+1, ×4+1, ×5+1 ……..

So, 440 is replaced by 446

5, 6, 14, 40, 89, 170, 291

Solution : +12, +32, +52, +72, +92

So, 14 is replaced by 15.

445, 221, 109, 46, 25, 114, 4

Solution : -3÷2, -3÷2……..

So,46 is replaced by 53.

12, 26, 56, 116, 244, 498, 1008

Solution : ×2+2, ×2+4 ×2+6,  ……..

So, 116 is replaced by 118

8, 27, 64, 125, 217, 343

Solution : 23, 33, 43, 53,…..

So, 217 is replaced by 216

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