• $X$ is 5.
  • $U$ is 9.
  • $O$ is 0 or 7.
  • $I$ is 4 or 5 or 7.

What is $V$? And what is $K$ (two options)?

  • $\begingroup$ Inspired by this puzzle, but the underlying pattern is not the same. $\endgroup$ – Rand al'Thor Jun 9 at 20:42

I think that

$V$ is $2$
$K$ is $1$ or $3$


Find the elements in the periodic table whose chemical symbol begins with the letter. The associated numbers are those in the tens position of the corresponding atomic numbers.


$X \rightarrow$ is Xenon (Xe) whose atomic number is 54
$U \rightarrow$ Uranium (U) with atomic number 92
$O \rightarrow$ Oxygen (O) and Osmium (Os) with atomic numbers 08 and 76
$I \rightarrow$ Indium (In), Iodine (I) and Iridium (Ir) with atomic numbers 49, 53, 77
$V \rightarrow$ Vanadium (V) with atomic number 23
$K \rightarrow$ Potassium (K) and Krypton (Kr) with atomic numbers 19 and 36.

Note: Oganesson (Og) has not been included here, either it is too new or we are only considering elements less than 100.

  • 1
    $\begingroup$ Brilliant! You got it. (I was expecting this one to be solved quicker - just came now to add a hint.) $\endgroup$ – Rand al'Thor Jun 13 at 8:09

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