Series - How to Find Missing Number

Series Is a set or sequence of elements which may be numbers, letters, symbols etc… which either follow a particular pattern or has an internal logic between them. In general Number series and letter, series are asked in the exam.

Again in the number and letter series, there are

• MISSING NUMBER/LETTER SERIES 
• WRONG NUMBER/LETTER SERIES

Let us first discuss regarding number series. For some aspirants, number series is an easy and scoring topic but for some aspirants, it is t, e most difficult thing, Some can identify the logic between the numbers easily but for some, it is like is an irritating thing. As a set of 5 questions are asked in the exam we cannot afford to leave this topic. So for this regular practice is the key to success for this topic. First, let us divide the number series into following categories…

• Number based series
• Subtraction based series
• Multiplication based series
• Division based series
• Miscellaneous series

Practice this topic in an above-said manner. First, try the question whether it is a number based or Addition or difference based series then move on to the different categories.

To crack the series topic one should be perfect with Prime numbers, squares, cubes, squares of prime numbers, cubes of prime numbers.

SQUARES
1	1	26	676
2	4	27	729
3	9	28	784
4	16	29	841
5	25	30	900
6	36	31	961
7	49	32	1024
8	64	33	1089
9	81	34	1156
10	100	35	1225
11	121	36	1296
12	144	37	1369
13	169	38	1444
14	196	39	1521
15	225	40	1600
16	256	41	1681
17	289	42	1764
18	324	43	1849
19	361	44	1936
20	400	45	2025
21	441	46	2116
22	484	47	2209
23	529	48	2304
24	576	49	2401
25	625	50	2500

CUBES
1	1	8	512
2	8	9	729
3	27	10	1000
4	64	11	1331
5	125	12	1728
6	216	13	2197
7	343	14	2744
		15	3375

Number(N)	N2	N3	N2 +1	N2-1	N3-1	N3+1	Nn	Nn +1	Nn/2	N3+N	N3-N
0	0					1
1	1					2
2	4					9
3	3					28
4	16					65
5	25					126
6	36					217
7	49					344
8	64					513
9	81					730
10	100					1001

By remembering the vertical rows of the above table, aspirants would be benefited in identifying the difference pattern among the numbers. Now let us discuss some questions.

Question 1.   144, 196, 256, 324, 400, 484, -----

Question 2.   27, 125, 343, 729, -----

Question 3.   17, 19, 23, 29, 31, 37,------

Question 4.   64, 125, 216, 343, 512, 729,----

Question 5.   6241, 6889, 7921, ------, 10201

Question 6.   11, 22, 34, 47, 61, 76, -------

Question 7.   11, 12, 16, 25, 41, 66, ------

Question 8.  1, 2, 6, 30, 210, -------

Question 9.    83, 168, 339, 683, 1373, 2757, ,--------

Question 10.   6, 24, 120 , 336, 1320, 2184, -------

Question 11.   15, 21, 24, 30, 33, ,-------

Question 12.   43, 42, 40, 36, 33, ,--------

Question 13.   3240, 540, 108, 27, …….., 4.5. ( IBPS PO PRLIMS-2017)

Question 14.   7, 4.5, 5.5, 12, 49, -------( IBPS PO PRLIMS-2017)

Question 15.  17, 98, 26, 89, 35, -------- ( IBPS PO PRLIMS-2017)