This sequence goes on forever, but here is the first 7 of them. The X's are just there to hide the actual digits. Can you find all the correct digits of the 8th entry?

1024, 90X1X, 25023X, 490364, X1031X0, XX1041X4, X690XXXX, ________?


No complicated calculations needed. In fact, it's based on a very simple rule. I'm sure this sequence would've been solved within minutes if I didn't replaced the digits with X's.

More specific hint:

Squares involved

  • $\begingroup$ Does the use of 'X' represent the sameness of all digits? $\endgroup$ Jun 4 '20 at 17:03
  • $\begingroup$ @JohnBrookfields No, it doesn't. $\endgroup$ Jun 4 '20 at 17:06

The pattern is

1024, 90X1X, 25023X, 490364, X1031X0, XX1041X4, X690XXXX
1024, 90216, 250236, 490364, 8103100, 12104144, 16904196

Hence, the next number is


  • 5
    $\begingroup$ Why 05 in the middle vs. 04? $\endgroup$
    – El-Guest
    Jun 4 '20 at 17:08
  • 1
    $\begingroup$ Yes, that's also something that confused me. It seems like it increases every two numbers, but then 02 occurs thrice, so I'm not sure anymore. $\endgroup$
    – sedrick
    Jun 4 '20 at 17:10
  • 1
    $\begingroup$ @sedrick well done, but the mid number is incorrect. The mid numbers represents something else $\endgroup$ Jun 4 '20 at 17:15

The fist few digits represent the odd number squares and the last few digits represent the even number square. ($1^2$ and $2^2$, $3^2$and $4^2$ and so on.) So, the next number will be $22504256$. The numbers given are: $1024, 90216, 250236, 490364, 8103100, 12104144, 16904196$ and finally $22504256$

  • $\begingroup$ Good work, but the mid number is not correct. Take a look on the comment section above $\endgroup$ Jun 4 '20 at 17:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.