Here is a number series puzzle from an IQ test.

$9876$, $5555$, $1234$, $?$

I would like to know what the next number, ($?$), is. I notice the pattern that all the digits are used in the series; maybe that's related. I'm thinking that the $?$ replaces something like $0000$ or $9999$, please help me.


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1234. Subtract the next term from the previous one and reverse the digits - 9876-5555=4321 -> 1234, so 5555-1234=4321 -> 1234.

  • $\begingroup$ @lioness If this is the correct answer, please remember to mark it as correct by clicking the green tick mark next to the answer. $\endgroup$ – F1Krazy Jan 6 at 16:48
  • $\begingroup$ @lioness I think the answer is -3087 as the numbers decrease by 4321 each time $\endgroup$ – a guy Jan 8 at 6:38

Here is the series: $9876$, $5555$, $1234$, $?$

$9-5$ = ***4
$8-5$ = **34
$7-5$ = *234
$6-5$ = 1234

An therefore;

$5-1$ = ***4
$5-2$ = **34
$5-3$ = *234
$5-4$ = 1234

  • $\begingroup$ This answer doesn't make much sense - you haven't explained anything using English words. You also haven't answered the question directly: what number replaces the $?$? In addition, it looks like JonMark Perry answered this question below. Although I don't want to make any calls, it looks like your answer is identical to his. $\endgroup$ – Hugh Jan 4 at 23:16
  • $\begingroup$ you must subtract the first digit of the first number with the first digit of the second number and put the result at the end, in reverse order. Then you subtract the second digit of the first number with the second digit of the second number and rewrite it in reverse order. the same thing also for the third and fourth digit. The solution is the same but the procedure is different. $\endgroup$ – nonsochedire Jan 5 at 0:10
  • $\begingroup$ ...which is basically the same as JonMark Perry's answer below? $\endgroup$ – Hugh Jan 5 at 0:39