A mathematic riddle:

If $1+9+8=1$, what is $2+8+9$?

I know, many of you out-of-the-box-thinkers, I really like it,
but please don't give answers to this riddle as $1=0$ and $9=0$ and $8=1$, that's why $1+9+8=1$.

Good luck!

As it has been solved here is the link for the puzzle.

  • $\begingroup$ This doesn't seem to be your riddle, looking it up online comes back with dozens of hits, so could you show where you found it? $\endgroup$ Aug 19, 2020 at 16:09
  • $\begingroup$ Yes, but it has the answer with it. $\endgroup$
    – math scat
    Aug 19, 2020 at 16:11
  • 1
    $\begingroup$ For sources that provide the answer, mention that the puzzle is from elsewhere and then add the source once the puzzle is solved. See here $\endgroup$ Aug 19, 2020 at 16:13
  • 1
    $\begingroup$ Just realised this is actually a duplicate on PSE - d'oh! See Number related puzzle. But not even close to math. What is it? Totally didn't spot that before I answered (and only thought to check at all because BG spotted it elsewhere on the web)... $\endgroup$
    – Stiv
    Aug 19, 2020 at 16:14

1 Answer 1


2 + 8 + 9 is:



We need only look at the first letters of each number when spelled out as words:

One + Nine + Eight = ONE (1)


Two + Eight + Nine = TEN (10)


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