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Wrong Number Series: Sometimes, a question is asked to find out the wrongnumber in a series. This is a bit difficult task. This is because from the pointwhere you get a wrong number, all other succeeding numbers would also be lookwrong. You can only solve such a question comfortably only if you have expertisein handling the questions on series very well. See the following example.

Example No. 1: ind the wrong number in the following series.!" #$ $% &! &" && &'Solution: (n this question, if you start from the beginning, firstly the difference is%!, then the difference is !&, then the difference is '. So there is no logic. (f youstart backwards,you can see that firstly, ! is added, then ) is added, then # isadded, then ',!$ and %) should have been added. So you have got the right clue.So !" * %) the first number should be #& and afterwards, the series becomes *!$, * ', * #and so on.

Example No. 2: ind the wrong number in the following series.!+ )! #% '" !&"

Solution:(n this question, the logic involved is ) * ! only.-ut the error lieswhere instead of #% ) * ! '&, '" has been given. So '" is the wrong number.

* Replacing the Wrong Number: Sometimes, the question is related to notonly finding the wrong number, but also with finding the number which shouldreplace the wrong number identified. You can see the following example.

Example No. 3: (n the following series, a wrong number is given. ind out thatwrong number, and decide which option should replace that wrong number.

! # ' / )" !$ $#

Solution: (n this sequence, two consecutive series are going simultaneouslyrelating to perfect cubes and perfect squares respectively. irstly ! cube is given,then ) cube is given,then % cube should have been there which should be )&, but)& is written at that place. 0nd then there is the cube of #, i.e $#. 0nd the seriesgiven is alternately square of ), then square of % and then square of # and so on.You may note this that in order to increase the confusion, the wrong number isalso a perfect square.

Example No. 4: (n the following series, a wrong number is given. ind out that wrongnumber, and decide which option should replace that wrong number.

Solution:(n this question the series is related to * ), * %, * # and then there is* # again, then * &, it seems odd. (nstead of second * # there should be * ".This means !# * " 1 !/, should be there instead of !'. 0nd thereafter, theseries would become * $ and * & and it would be a right logical series. So !/ isthe answer.

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Tin Series: This is a newly included type of series in which two series aregiven, and below that the starting point of another series is given. 2ow you aresupposed to analy3e the logic from the first series and apply the same logic toform the second series,and answer the question given below the second series.See the following example.

Example No. 1: (n the following question a series is given and it is followed bythe starting point of another series. 0fter this, a question is given, you have tocomplete the second series by applying the same logic as in the first given series,and then you have to answer the question. " ' !) !& )% %+ / a b c d e4hich number should come in place of c5Solution:(n this question, it canbe analy3ed that the difference between thenumbers is %, #, ", $ and &. So youhave to apply the same logic and start theseries with /. The first numberafter / would be / * % !) 6this would replaceletter a7, the second numberwould be !) * # !$ 6this would replace letter b7and the third number wouldbe !$ * " )! 6this would replace the letter c7. Youneed not to go furtherbecause the question is related to c only.

Example No. 2: (n the following question, a series is given and it is followed bythe starting point of another series. 0fter this a question is given, you have tocomplete the second series by applying the same logic as in the first given series,and then you have to answer the question.

' / !% )) %' $% !) a b c d e4hich number should come in place of d5Solution:(n this question, the squares of the natural numbers are added. irstly! is added, then #, then /and so on. You have to apply the same logic and add !,#, / and !$ to get the value of d. 0fter adding !, you8ll get !% which is the valueof a, then after adding # you8ll get !&, which is the value of b, after an addition of/ you8ll get )$ which is the value of c.0fter this add !$ and get #), which is thevalue of d.

Example No. 3: (n the following question, a series isgiven and it is followed bythe starting point of another series. 0fter this a question is given, you have tocomplete the second series by applying the same logic as in the first given series,and then you have to answer the question. ) % " & !! !% )% a b c d e4hich number should come in place of b5Solution:(n this case, it can be seen that the series is of prime numbers. 0s thesecond series is starting from)%, the next prime number is )/ 6which is at theplace of a7, thereafter the next prime number is %! 6which would be at the place

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of b7 and is the right answer.

Some other common types of number series involve the following types of logic:

!.9rime 2umbers: E!"#$%E : 3&'& (& 11& 13& 1(& ) 1+,

).Successive 0ddition, eletion, ;ultiplication etc.

E!"#$%E: 4& -& 1& 1-& 24& 34& /)...- "00 2& 4& -& & 1& / 4-,

%. 0dding different numbers at regular intervals:

E!"#$%E: 1(& 23& 2+& 3'& /.)/..& 4( "00ing - each time 6417

E!"#$%E: & 23& 44&//&14& 143 "00ing 1'& 21& 2(& etc. haing a ixe0 gapo - each6(17

#.0dding< deleting prime

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4e have to find the number which is a misfit in the series. 0s illustrated above, the lastnumber in the series should have been $)#+, which is not there. Therefore, $)"+ is thecorrect answer.