This is my real date of birth, because it looks unique, I try to do a simple operation, and I get a number 222.

In fact it is able to solved without looking at the hint, but I'm trying to make this puzzle easy.


??+?4+,?4+,?4 = 141

When is my date of birth? And how is the number 222 obtained from the calculation results?

  • The main purpose of this puzzle is not just for someone to answer it, but I hope someone can also improve what is needed
  • 2
    $\begingroup$ What? I don't understand the question here. Is the puzzle "find a date of birth (sequence of three numbers) which can be operated on to give the number 222"? That seems way too broad. And what does the 141 have to do with it? $\endgroup$ – Rand al'Thor May 6 '18 at 15:16
  • $\begingroup$ sorry if I am wrong, but the question has been successfully answered when I put in social media, I put it here for someone to improve it, what do I need to add? $\endgroup$ – Q̞ī̯X̶͇͇͇͇͇͇͇͇͇͇͇͇͇̯̯̳̳͈͈͈͆͆ May 6 '18 at 15:27
  • $\begingroup$ The ?s in the 141 part appear to be the date in YYYY, MM, DD form. The entire date can be deduced from that hint. I'm still trying to make sense of the 222 part. $\endgroup$ – Apep May 6 '18 at 15:31

From the hint:

We start from $??+?4+?4+?4 = 141$, or in better notation $AB+C4+D4+E4 = 141$.

  • Taking everything modulo 10, we get $B+12\equiv1$, so $B=9$.

  • Since $D4$ is a month, we must have $D=0$ (there is no 14th month).

  • Assuming you're not from the distant past or future (e.g. born in the 10th or 30th century), we must have $A=1$.

  • Now the equation is $19+C4+04+E4=141$, so $C+E=11$. We also know that $E$ must be $0$ or $1$ or $2$, so the only option is $C=9,E=2$.

So your date of birth is

1994/04/24 or 24 April 1994.

If you want feedback, I would say that this isn't doable without the hint. Certainly not uniquely solvable, when you don't specify what types of operations are allowed. Following this site's generic advice on questions, I'd advise you to restrict the possible operations which are permitted to be used in getting from the birthdate to 222. E.g. is it just $+,-,\times,\div$? Are $\sqrt{},!,\lfloor\,\rfloor, \exp$ also allowed? You need to have a clear finite list, otherwise there are too many thinking-outside-the-box possibilities.

  • $\begingroup$ Hmm, tbh I solved it without the hint.. Well, I "guessed" the date to be around 1994/1984 04 04/14/24 tho and just tried to find a good matching to get 222. $\endgroup$ – athin May 6 '18 at 15:49
  • $\begingroup$ I know it's easy to solve, is there another way to make it more difficult as not showing the number 4? $\endgroup$ – Q̞ī̯X̶͇͇͇͇͇͇͇͇͇͇͇͇͇̯̯̳̳͈͈͈͆͆ May 6 '18 at 16:03

The answer is

$1994, 04, 24$; or April 24th, 1994.


$\lfloor \sqrt{1994 \times 24} + 4 \rfloor = 222$

  • 2
    $\begingroup$ Nice find! +1. I'm just a bit worried about the use of $\lfloor\,\rfloor$ though: it makes this seem a bit arbitrary, since all you really need then is to construct a number somewhere close to $222$ using the birth date. $\endgroup$ – Rand al'Thor May 6 '18 at 15:48
  • $\begingroup$ Agreed, using floor function is not a really nice practice actually... $\endgroup$ – athin May 6 '18 at 15:51
  • $\begingroup$ right, but the number 222 of the calculations is unlike that, the number 222 is closely related to the hint $\endgroup$ – Q̞ī̯X̶͇͇͇͇͇͇͇͇͇͇͇͇͇̯̯̳̳͈͈͈͆͆ May 6 '18 at 16:13

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