Results 1 to 16 of 16

Thread: Missing number in the series

  1. #1
    Contributing Member
    Join Date
    Jul 2006
    Answers
    74

    Missing number in the series

    What is the missing number in the series?
    4,9,20,43,90??


  2. #2
    Expert Member
    Join Date
    Jun 2006
    Answers
    410

    Re: Missing number in the series

    Ans: 185.

    diff between 4 and 9 is 5 (4+1)
    diff between 9 and 20 is 11 (9+2)
    diff between 20 and 43 is 23 (20+3)
    diff between 43 and 90 is 47(43+4)


    -- James


  3. #3
    Contributing Member
    Join Date
    Jul 2006
    Answers
    74

    Re: Missing number in the series

    James your approach is prefect and the solution for this problem is 185 as you found out.


  4. #4
    Junior Member
    Join Date
    Jan 2009
    Answers
    3

    Re: Missing number in the series

    Quote Originally Posted by scott View Post
    What is the missing number in the series?
    4,9,20,43,90??
    Another approach

    (4*2) + 1 = 9
    (9*2) + 2 = 20
    (20*2) + 3 = 43
    (43*2) + 4 = 90
    (90*2) + 5 = 185


  5. #5
    Expert Member
    Join Date
    Nov 2008
    Answers
    300

    Re: Missing number in the series

    yep

    current No - (90 + 5)

    Prev No - 90

    so 90 + 95 = 185


  6. #6
    Junior Member
    Join Date
    Mar 2007
    Answers
    2

    Missing number in the series

    Quote Originally Posted by scott View Post
    What is the missing number in the series?
    4,9,20,43,90??
    the next no of the series is 143

    Last edited by sadaf; 05-14-2009 at 07:35 AM.

  7. #7
    Junior Member
    Join Date
    Mar 2007
    Answers
    2

    Missing number in the series

    Quote Originally Posted by scott View Post
    What is the missing number in the series?
    4,9,20,43,90??
    the last no of the series is 143


  8. #8
    Junior Member
    Join Date
    Jun 2009
    Answers
    1

    Cool Re: Missing number in the series

    4 9 20 43 90 ?

    the difference

    4 9 20 43 90 ?

    5 11 23 47 ?

    6 12 24 48

    so the 3rd series is 6 12 24 (48) it doubles the digit.. adding 48 in 47 so the figure is 95 now we got main difference series.....adding 95 in main series 90 then ans is 185.


  9. #9
    Expert Member
    Join Date
    Jun 2007
    Answers
    260

    Re: Missing number in the series

    Hi,

    The missing number is 185.

    Here is the explanation

    4 9 20 43 90

    9-4=5
    20-9=11
    43-20=23
    90-43=47

    (5*2)+1=11
    (11*2)+1=23
    (23*2)+1=47

    so, in the same way (47*2)+1=95

    So, x-95=90.

    Therefore x= 185.

    Thanks


  10. #10

    Smile Re: Missing number in the series

    Quote Originally Posted by scott View Post
    What is the missing number in the series?
    4,9,20,43,90??
    please find the steps


  11. #11

    Re: Missing number in the series

    answer is 186


  12. #12

    Re: Missing number in the series

    answer is 186&379


  13. #13
    Junior Member
    Join Date
    Oct 2010
    Answers
    1

    Re: Missing number in the series

    How can I draw up a formula that number series?

    4,9,20,43,90??
    Thank you!


  14. #14
    Junior Member
    Join Date
    Dec 2010
    Answers
    1

    Re: Missing number in the series

    Hi Isabele,

    The formula is defined as
    The difference between 9-4= 4+1 is 5
    20-9=(5+5)+1 is 11
    43-20=(11+11)+1 is 23
    90-43=(23+23)+1 is 47
    185-90=(47+47)+1 is 95
    so the answer is 90+95(add last number+difference number) = 185


  15. #15
    Junior Member
    Join Date
    Dec 2010
    Answers
    6

    Re: Missing number in the series

    4 + 4 + 1 = 9
    9 + 9 + 2 = 20
    20 + 20 + 3 = 43
    43 + 43 + 4 = 90
    90 + 90 + 5 = 185


  16. #16
    Junior Member
    Join Date
    Mar 2016
    Answers
    2

    Re: Missing number in the series

    185
    In this series each 2nd no is incremented by 1 with double of the previous number.
    9=4*2+1
    20=9*2+2
    43=20*2+3
    90=43*2+4
    so, next number will be 185 as
    185=90*2+5


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
About us
Applying for a job can be a stressful and frustrating experience, especially for someone who has never done it before. Considering that you are competing for the position with a at least a dozen other applicants, it is imperative that you thoroughly prepare for the job interview, in order to stand a good chance of getting hired. That's where GeekInterview can help.
Interact