What would be the next digit that follows these numbers?

1, 11, 20, 30, 7, 49, 42, 23, 3, ?

Just so it's clear, you won't need any mathematics to solve this at all! In fact, everything you need is here.

  • $\begingroup$ so no math or lateral thinking needed? hmmm... $\endgroup$ Nov 11, 2016 at 8:47
  • 2
    $\begingroup$ A little thinking outside the box is definitely required, but I left off the 'lateral thinking' tag to discourage answers like "this sequence is the number of footsteps needed to cover the width of a soccer field in New South Wales!". $\endgroup$
    – Xenocacia
    Nov 11, 2016 at 8:52
  • $\begingroup$ When you say next digit are you saying the next number is one digit or you want the first digit of the next number (which may be 10 or more)? $\endgroup$
    – boboquack
    Nov 11, 2016 at 9:01
  • 2
    $\begingroup$ I'm pretty sure I've solved it, but that there is a 42 missing between 49 and 23. $\endgroup$ Nov 11, 2016 at 9:02
  • 1
    $\begingroup$ @JonathanAllan, thank you for spotting that error, and damn that was quick! $\endgroup$
    – Xenocacia
    Nov 11, 2016 at 9:06

3 Answers 3


I think the answer is



If you read only the alphabetic characters of the question each number in the sequence is the first occurrence of a letter ordered by the alphabet:
A is first found at index 1 - Asimple...
B is first found at index 11 - ...numB...
C is first found at index 20 - ...ersequenCe...
D is first found at index 30 - ...whatwoulD...
E is first found at index 7 - asimplE...
F is first found at index 49 - ...nextdigitthatF...
G is first found at index 42 - ...nextdiGitthat...
H is first found at index 23 - ...sequencewHatwould...
I is first found at index 3 - asImple...
J is first found at index 68 - ...thatfollowsJustsoitsclear...

  • $\begingroup$ Ah, you were just a second earlier. You counted the ? as well? $\endgroup$
    – Levieux
    Nov 11, 2016 at 9:07
  • 4
    $\begingroup$ I thought this would stump the community for a little longer than this. Guess I underestimated Puzzling SE. Congratulations! $\endgroup$
    – Xenocacia
    Nov 11, 2016 at 9:09
  • $\begingroup$ @Levieux you were faster answering but he commented abov 9 min ago $\endgroup$
    – lois6b
    Nov 11, 2016 at 9:12
  • $\begingroup$ @Levieux oh, nope - I just can't count near that number without Bill & Ted influencing my numeracy. Thanks! $\endgroup$ Nov 11, 2016 at 9:15

I would say it's

68: The position of the first occurrence of the letter J.


Here is an attempt.

If it is a simple number sequence and everything we need is here and no math is needed.
Perhaps it is just that, 1 full complete sequence of number.
That would mean that the next number would be "1" since the first sequence if over and we start a new loop.
For example, if we say 4,1,3,4,1,3,? then the answer is 4

  • 2
    $\begingroup$ Nice try, but nope. That would be too lazy on my part, wouldn't it? :) $\endgroup$
    – Xenocacia
    Nov 11, 2016 at 8:41

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