Number Series
Number Series
INTRODUCTION: This topic consists of questions in which series of numbers or alphabetical letters or combinations of both are given, which are generally called the terms of the series. These terms follow a certain pattern throughout the series. The candidate is required to study the given series, identify the patterns followed in the series and either complete the given series with the most suitable alternative or find the wrong term in the series.
TYPE 1:
Case I: Completing The Given Series By Finding The Missing Term(s)
Directions: Find the missing term in each of the following series:
Illustration 1: 1, 6, 15, ?, 45, 66, 91
(a) 25 (b) 26 (c) 27 (d) 28
Solution: Clearly, the given sequence follows the pattern : + 5, + 9, + 13, + 17, + 21, + 25,........
Thus, 1 + 5 = 6, 6 + 9 = 15, ........
So, missing term = 15 + 13 = 28.
Hence, the answer is (d).
Illustration 2: 2, 5, 9, 19, 37, ?
(a) 73 (b) 75 (c) 76 (d) 78
Solution: Clearly, we have : 2 X 2 + 1 = 5, 5 X 2 - 1 = 9, 9 X 2 + 1 = 19, 19 X 2 - 1 = 37, ....
So, missing term =
Hence, the answer is (b).
Illustration 3: 10000, 11000, 9900, 10890, 9801,?
(a) 10241 (b) 10423 (c) 10781 (d) 10929
Solution: Clearly , alternatively we add and subtract 10% of a term to obtain the next term of the series.
Thus, 10000 + (10% of 10000) = 11000, 11000 - (10% of 11000) = 9900,
9900 + (10% of 9900) = 10890, 10890 - (10% of 10890) = 9801.
So, missing term = 9801 + (10% of 9801) = 9801 + 980 = 10781.
Hence, the answer is (c).
90, 84, 86, 80, ----------, 76, 78 | |||
| Right Option : B | |||
| View Explanation | |||
Find the missing term: 7, 8, 12, 21, 37, ______. | |||
| Right Option : C | |||
| View Explanation | |||
2, 5, 9, ?, 20, 27 | |||
| Right Option : A | |||
| View Explanation | |||
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