Back in high school, I thought of a code to secretly communicate with a few of my close friends. The key to this code is excessively and readily available by using google in 1 second if you know what to search for.

  • "What-is-this?" can be encoded as 74185-5316-905316?
  • "teacher" is 5289168
  • "poses" can be encoded as either 1583416 or 1581699 or 843416 or 841699

There are limitations with this code though:

  • "close" can be encoded as 17834 but "lose" cannot
  • "tier" or "ties" can be encoded but "tie" cannot
  • "a-cat" cannot be encoded so we had to use "one-cat" (810-685)
  • "i-love-you" cannot be encoded so "i-luv-u" had to be used (53-7123-92)

Anyone guess where this code comes from? If you do know, how can I make this coding more complete as currently there are quite many words which cannot be encoded?


I and these close friends later all went to university and applied to courses that related to the same subject.


1 Answer 1


You've encoded your messages with

the Periodic Table of Elements, by substituting atom symbols for their atomic numbers.

For example

W-H-At I-S Th-I-S = 74-1-85 53-16 90-53-16
W = Tungsten (74)
H = Hydrogen (1)
At = Astatine (85)
I = Iodine (53)
S = Sulfur (16)
Th = Thorium (90)

And the hint:

You all studied either chemistry or physics.

To extend your code, you can either use the proposal by Xenocacia in the comment below, or

take advantage of the fact that the largest elements (>118) haven't been discovered and above a certain number probably will never be, because they're too unstable. Basically all three digit codes above 150 are free to use as you want.

  • 2
    $\begingroup$ The code can be made more complete (not harder to break) by having every letter be a 3-digit code. The first 2 digits will be the corresponding number as above (0x if single-digit), with the 3rd digit pointing to a specific letter. E.g. the letter C could be 061, or 201, or 212. $\endgroup$
    – Xenocacia
    Feb 2, 2017 at 10:00
  • 3
    $\begingroup$ Wolframium? I though it was Tungsten... $\endgroup$
    – boboquack
    Feb 2, 2017 at 20:30
  • 1
    $\begingroup$ Thanks, I used the Latin name instead of the English name. (In Dutch, we call it Wolfraam.) $\endgroup$
    – Glorfindel
    Feb 2, 2017 at 20:32
  • $\begingroup$ Wow, you found out this quite fast Glorfindel, are you interested in Chemistry too? To be extended the code has to go up to 3 digits that's for sure, but it needs to have an underlying rule that is consistent. Assigning letters to numbers above 150 would be a bit random as in the end, it is intended for whoever wants to crack the code to know/look up the periodic table. $\endgroup$ Feb 3, 2017 at 0:40
  • $\begingroup$ Xenocacia's suggestion might work but there is problem: every letter would need 3 digits, which means a code that is 3 times longer than the actual word (for e.g: teacher currently is 5289168, but with the new rule it'd be 21-digit long). And it would also eliminate some of the neat feature the code already has: "He" is 2 (Helium) but with the new rule it'd become 011022, I mean there are groups of 2 letters that already exist in the periodic table (Li, Be, Ne, Na, Co, Se, etc...) which have its own 'code', if we follow the new rule, we kinda throw this away. $\endgroup$ Feb 3, 2017 at 1:00

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