Question : Directions: Select the number from among the given options that can replace the question mark (?) in the following series.
28, 27, 31, 22, 38, 13, 49, ?
Option 1: 42
Option 2: 2
Option 3: 0
Option 4: 22
Correct Answer: 0
Solution :
Given:
28, 27, 31, 22, 38, 13, 49, ?
Subtract and add alternately the square of consecutive natural numbers –
28 – (1)
2
= 28 – 1 = 27
27 + (2)
2
= 27 + 4 = 31
31 – (3)
2
= 31 – 9 = 22
22 + (4)
2
= 22 + 16 = 38
38 – (5)
2
= 38 – 25 = 13
13 + (6)
2
= 13 + 36 = 49
49 – (7)
2
= 49 – 49 = 0
So, 0 is the missing number of the series. Hence, the third option is correct.
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