I have four coins, all of which are United States currency, on my desk. Some of these coins are face up, and the rest are face down. I know the following facts about the four coins:

1) Each of the four coins is just less than 2 centimeters in diameter.

2) The oldest coin of the four is from 1983.

3) From my perspective (i.e. yours as well), I can see four different drawings on each of the four coins.

4) From my perspective (i.e. yours as well), I can see 7 letter M's.

Your task is to identify each of the four coins and specify whether they are face-up or face-down.

  • $\begingroup$ "From my perspective (i.e. yours as well), I can see 7 letter M's." Do you mean that they're upright facing you? Or can they be facing another side of the desk? $\endgroup$ – msh210 Jul 23 '19 at 5:02
  • $\begingroup$ Gurer ner bayl 2 xvaqf bs pbva jvgu guvf qvnzrgre. Gurve snprf ner nyjnlf gur fnzr, gurer onpxf nyjnlf ubyq gur fnzr grkg. Bar bs gur pbvaf pna unir 6 qvssrerag onpxf, nyy jvgu gur fnzr ahzore bs Zf, jr pna'g gryy gurz ncneg. Obgu pbvaf' snprf unir ab Zf, jr pna'g gryy gurz ncneg. Vg'f xvaqn uneq gb "vqragvsl" gurz haqre gurfr pbaqvgvbaf. $\endgroup$ – Dorian Fusco Jul 23 '19 at 8:36
  • $\begingroup$ msh210: They're upright, facing me. Dorian Fusco: rot13(V bayl ernyvmrq na ubhe yngre gung gurer pbhyq or gjb cbffvovyvgvrf sbe gur nafjre, ohg V pbhyqa'g rqvg gur ceboyrz ol gura. Bbcf.) $\endgroup$ – Cloudy7 Jul 23 '19 at 14:49

I don't know USA coins, but:

Only 10¢ and 1¢ are less than 2 centimeters in diameter, so I guess it could be just:
(1) 1 (2) 2
(3) 3 (4) 4
(5) 5
So if I can see it correctly, it has to be 1,3 and 4. First has 3 x M, third and fourth both 2 x M, so in total 7 x M. Last coin can be second or last one.

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  • $\begingroup$ I'm pretty sure you went to Wikipedia to find these, that's where I went too, as I don't know US coins either. There are 4 missing designs for the 1¢ coins (dated of 2009), Wikipedia lists them but doesn't show them. They could be relevant for the solution, they all have 2 M lincolncents.net/wp-content/uploads/2009/07/… $\endgroup$ – Dorian Fusco Jul 23 '19 at 8:11
  • $\begingroup$ But the first coin, for example, has its three Ms facing three different directions. The OP mentioned in a comment on the question that they're all facing the same direction. $\endgroup$ – msh210 Sep 15 '19 at 13:22

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