Number Series
Direction: In the following number series only one is wrong. Find out the wrong number.
 7, 4, 5, 9, 20, 51, 106.5

 4
 5
 9
 20
 51

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The series is x 0.5 + 0.5, x 1 + 1, x 1.5 + 1.5. x 2 + 2, x 2.5 + 2.5, x 3 +3
Correct Option: E
The series is x 0.5 + 0.5, x 1 + 1, x 1.5 + 1.5. x 2 + 2, x 2.5 + 2.5, x 3 +3
 18, 20, 23, 32, 48, 73, 109

 20
 23
 32
 48
 73

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The series is 18 +1^{2} = 19; 19 + 2^{2} = 23; 23 + 3^{2} = 32;
32 + 4^{2} = 48; 48 + 5^{2} = 73 + 6^{2} = 109Correct Option: A
The series is 18 +1^{2} = 19; 19 + 2^{2} = 23; 23 + 3^{2} = 32;
32 + 4^{2} = 48; 48 + 5^{2} = 73 + 6^{2} = 109
 3, 7, 16, 35, 72, 153, 312

 7
 153
 35
 72
 16

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The series is x 2 + 1, x 2 + 2, x 2 + 3, x 2 + 4, x 2 + 5
Correct Option: D
The series is x 2 + 1, x 2 + 2, x 2 + 3, x 2 + 4, x 2 + 5
 2, 7, 30, 138, 524, 1557, 3102

 7
 30
 138
 524
 1557

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(2  1) x 7 = 7; (7  2) x 6 = 30; (30  3) x 5 = 135; (135  4) x 4 = 524;
(524  5) x 3 = 1557; (1557  6) x 2 = 3102Correct Option: C
(2  1) x 7 = 7; (7  2) x 6 = 30; (30  3) x 5 = 135; (135  4) x 4 = 524;
(524  5) x 3 = 1557; (1557  6) x 2 = 3102
 6, 10, 14, 34, 66, 130, 258

 10
 14
 34
 66
 130

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The series is x 2  2, x 2  2, x 2  2, x 2  2, ......
Correct Option: B
The series is x 2  2, x 2  2, x 2  2, x 2  2, ......