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Fill in the missing number

 
 
Reply Tue 2 Feb, 2016 11:01 pm
What number is missing from this series?

5 , 15 , 35 , ... , 355
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Type: Question • Score: 3 • Views: 1,138 • Replies: 10
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boomerang
 
  1  
Reply Wed 3 Feb, 2016 06:54 am
@ascribbler,
155?
Ragman
 
  1  
Reply Wed 3 Feb, 2016 04:33 pm
@ascribbler,
175?
ascribbler
 
  0  
Reply Wed 3 Feb, 2016 11:45 pm
@boomerang,
Would you please show how your answer was determined?
0 Replies
 
ascribbler
 
  0  
Reply Wed 3 Feb, 2016 11:46 pm
@Ragman,
Would you please show how your answer was determined?
puzzledperson
 
  0  
Reply Thu 4 Feb, 2016 01:03 am
@ascribbler,
The first thing that I noticed was that all of the digits are odd and that within each number the digits are in numerical order.

The second thing I noticed is that the third and fifth numbers contain only the digits 3 and 5, and that the fifth number is the same as the third with the addition of a 5.

So one interpretation is that this is a nested double sequence with the first two numbers acting as seed values (the first number for the first sequence, and the second number for the second sequence). The second term of the first sequence adds a prefix digit, while the second term of the second sequence adds a suffix digit. Therefore each sequence alternates between prefix and suffix digits with each term, while always being opposite to one another in that respect.

The fourth number could be 115 (being the second term of the second sequence it adds a suffix digit). The series could continue:

5, 15, 35, 155, 355, 1155, 3355, 11555...

This is a weakly inferred pattern but seems logically consistent.

I find that numerical pattern puzzles can be amenable to more than one solution. It could also be the case that your sequence is not a puzzle at all but simply random.
0 Replies
 
Ragman
 
  2  
Reply Thu 4 Feb, 2016 08:48 am
@ascribbler,
no.
0 Replies
 
ascribbler
 
  0  
Reply Fri 5 Feb, 2016 01:41 am
The series is:

5 , 15 , 35 , 75 , 355
0 Replies
 
mark noble
 
  0  
Reply Fri 5 Feb, 2016 10:43 am
@ascribbler,
The answer is 75

5 (No symbol) divided by 5 = 1
Place 1 b4 5 = 15
15 (No symbol) divided by 5 = 3
Place 3 b4 5 = 35
35 (No symbol) divided by 5 = 7
Place 7 b4 5 = 75
75 (No symbol) divided by 5 = 15
Place 15 b4 5 = 155
155 (No symbol) divided by 5 = 31
Place 31 b4 5 = 315.

I think you posted the wrong numbers, scribbler. Mine are better.
ascribbler
 
  0  
Reply Fri 5 Feb, 2016 10:37 pm
@mark noble,
Quote:
I think you posted the wrong numbers, scribbler. Mine are better.


It's not a geometric progression.

There is no typographical or logical error in the question or the answer.

Quote:
The series is:

5 , 15 , 35 , 75 , 355


mark noble
 
  0  
Reply Sat 6 Feb, 2016 06:22 am
@ascribbler,
I agree.
But I got the '75', did I not?

Without the 'key' a door cannot be opened easily.

Try this: Which number is missing?

10 .. 12 14 ?
0 Replies
 
 

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