SERIES
A Series / Sequence contains various terms where in every term is connected with each other by a specific pattern / relationship. The tactics to solve such question is looking into the patter we should recognize the relation that exist between the terms.
There are two type of such series ::
1. ALPHABET SERIES :- Each English alphabet can be seen as having some relative position with respect to each other . The question has either individual letter series or sequence of combination of letters. All terms follow a pattern.
$\begin{array}{|C|C|C|C|C|C|C|C|C|C|C|C|C|}\hline A &B&C&D&E&F&G&H&I&J&K&L&M \\ 1&2&3&4&5&6&7&8&9&10&11&12&13 \\ \hline\\ \hline N &O&P&Q&R&S&T&U&V&W&X&Y&Z \\ 14&15&16&17&18&19&20&21&22&23&24&25&26 \\ \hline \end {array}$
2. NUMBER SERIES : Number series is generally created by performing simple mathematical operation like addition , subtraction , multiplication or division on any term in a particular patter to generate next term in series. $ Like $ 3 ,5 , 8 , 12 the what will be next, i.e 18
EXAMPLE 1 :- Find the missing number in the following series 10 ,20 ,31 ,43 , 56 ? \begin{align}\\ (A)\;69 \qquad\qquad \qquad (B)\;70 \qquad \qquad \qquad (C)\; 71 \qquad \qquad \qquad (D)\;72 \\ \end{align} Answer :- (B) $ \quad $The difference between the numbers is increasing by 1 $$ 10\; \overset{\mbox{+10}}{\longrightarrow}\; 20\; \overset{\mbox{+11}}{\longrightarrow}\; 31\; \overset{\mbox{+12}}{\longrightarrow}\; 43\; \overset{\mbox{+13}}{\longrightarrow}\; 56\; \overset{\mbox{+14}}{\longrightarrow}\; 70 $$ $$ $$ EXAMPLE 2 :- How many letters are there in BACKLASH which has same position in English alphabet from beginning as in the word ? \begin{align} \\ (A)\; 0\qquad\qquad \qquad (B)\; 1 \qquad \qquad \qquad (C) \;2 \qquad \qquad \qquad (D)\; 3 \\ \end{align} Answer :- (C) C , H at 3rd and 8th position in the word has same position in alphabet. $$ $$ EXAMPLE 3 :- If a series of English alphabet is written by deleting every 3rd letter in English alphabet starting from C then which will be the 9th letter in the series from the end ? \begin{align} \\ (A) \;K\qquad\qquad \qquad (B) \;N \qquad \qquad \qquad (C) \;P \qquad \qquad \qquad (D)\;Q \\ \end{align} Answer :- (B) The sequence will be A B D E G H J K M N P Q S T V W Y Z $$ $$ EXAMPLE 4 :- Find the wrong term in the following number series 90 , 55 , 88 , 58 , 84 , 61 , 81 , 64 ? \begin{align} \\ (A) \;88\qquad\qquad \qquad (B)\; 58 \qquad \qquad \qquad (C)\; 84 \qquad \qquad \qquad (D)\; 61\\ \end{align} Answer :- (A) $\quad \qquad \qquad 90\; \overset{\mbox{-3}}{\longrightarrow}\; 87\; \overset{\mbox{-3}}{\longrightarrow}\; 84\; \overset{\mbox{-3}}{\longrightarrow}\; 81 $ $$ AND \qquad 55\; \overset{\mbox{+3}}{\longrightarrow}\; 58\; \overset{\mbox{+3}}{\longrightarrow}\; 61\; \overset{\mbox{+3}}{\longrightarrow}\; 64 $$