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What is the next number in the following series - 9 , 19 , 39 , 79 , ??

+1 vote
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What is the next number in the following series - 9 , 19 , 39 , 79 , ??
posted Sep 1, 2014 by Deepak Chitragar

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5 Answers

+5 votes
 
Best answer

As per the given series ( 9, 19, 39, 79 .. ?)

next_number = (number + 10 * (1, 2, 4, 8, ..)), i.e

9  + (10 * 1) = 19
19 + (10 * 2) = 39
39 + (10 * 4) = 79
79 + (10 * 8) = 159

One more solution is:
next_number = (number * 2) + 1

9 * 2 + 1  = 18  + 1 ==> 19
19 * 2 + 1 = 38  + 1 ==> 39
39 * 2 + 1 = 78  + 1 ==> 79
79 * 2 + 1 = 158 + 1 ==> 159
answer Sep 1, 2014 by Arshad Khan
+3 votes

answer is 159

answer Sep 1, 2014 by anonymous
+3 votes

159
9x2+1=19,19x2+1=39,39x2+1-79,79x2+1=159

answer Oct 26, 2014 by Suresh Babu
+2 votes

(9*2) + 1 = 19
(19*2) + 1 = 39
(39*2) + 1 = 79
(79*2) + 1 = 159

So answer is 159
answer Nov 4, 2014 by Vigneshvari
0 votes

10 added to 9, to get 19.
Double of 10, 20 added to 19 to get 39.
Double of 20, 40 added to 39 to get 79.
Double of 40, 80 added to 79 to get 159.

answer Sep 2, 2016 by Vilas Joshi
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