In Choose odd Number questions, certain numbers are given, out of which all except one are alike in some manner while one is different and this number is to be chosen as the answer.
Choose or find odd number
7 , 15 , 31 , 57
Option:
A. 7
B. 15
C. 31
D. 57
Answer: D . 57
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Justification: All other numbers can be expressed as a power of 2 minus one. Thus 7 = 2³ - 1,
