Aptitude - Odd Man Out and Series - Discussion

Discussion Forum : Odd Man Out and Series - Missing No. (Q.No. 9)
Directions to Solve
Insert the missing number.

9.
4, -8, 16, -32, 64, (....)
128
-128
192
-192
Answer: Option
Explanation:

Each number is the proceeding number multiplied by -2.

So, the required number is -128.

Discussion:
5 comments Page 1 of 1.

Jethalal said:   5 years ago
Clear explanation, Thanks @Adil Maqbool.

Tushar saha said:   6 years ago
2*2 = 4.
4*(-2) = -8.
-8*-2 = 16.
16*-2 = -32.
-32*-2 = 64.
64*-2 = -128.
(1)

SHANIDUL Islam said:   7 years ago
2*4 = 8,
2*8 = 16,
2*16 = 32,
2*32 = 64,
64*2 = -128.

Areeba jawaid said:   8 years ago
Here, Every number is multiplied by (-2).

Adil Maqbool said:   1 decade ago
Alternate method.

We can form two series 4, 16, 64 & -8, -32,(....).

Multiply the previous digit by 4 to get the next number in the series.

e.g. 4*4 = 16, 16*4 = 64.

-8*4 = -32, -32*4 = -128.

Therefore -128 is the correct answer.

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