Arithmatical - Odd Man Out and Series

DIRECTIONS : Find out the wrong number in the series
6. 3, 7, 15, 27, 63, 127, 255
  A.  7
  B.  15
  C.  27
  D.  63
Solution
27.
Go on multiplying the number by 2 and adding 1 to it to get the next number. So 27 is wrong.
7. 2880, 480, 92, 24, 8, 4, 4
  A.  480
  B.  92
  C.  24
  D.  8
Solution
92.
Go on dividing by 6, 5, 4, 3, 2, 1 respectively to obtain the next number. Clearly, 92 is wrong.
8. 445, 221, 109, 46, 25, 11, 4
  A.  221
  B.  109
  C.  46
  D.  25
Solution
46.
Go on subtracting 3 dividing the result by 2 to obtain the next number. Clearly, 46 is wrong.
9. 7, 8, 18, 57, 228, 1165, 6996
  A.  8
  B.  18
  C.  57
  D.  228
Solution
228.
Let the given numbers be A, B, C, D, E, F, G. Then A, Ax1, Bx2+2, Cx3+3, Dx4+4, Ex5+5 ... and so on. are the required numbers. Clearly, 228 is wrong.
10. 1, 3, 10, 21, 64, 129, 356, 777
  A.  10
  B.  21
  C.  64
  D.  356
Solution
356.
Ax2+1, Bx3+1, Cx2+1, Dx3+1 and so on. So, 356 is wrong.
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