Enigma 1754: Elementary
19 June 2013
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From New Scientist #2922, 22nd June 2013 [link]
My textbook lists the two-letter symbols for chemical elements, including both old and new abbreviations for some of them, as:
Ac Ag Al Am Ar As At Au Ba Be Bh Bi Bk Br Ca Cd Ce Cf Cl Cm Co Cr Cs Cu Db Ds Dy Er Es Eu Fe Fm Fr Ga Gd Ge Ha He Hf Hg Ho Hs In Ir Kr La Li Lr Lu Lw Md Mg Mn Mo Mt Na Nb Nd Ne Ni No Np Os Pa Pb Pd Pm Po Pr Pt Pu Ra Rb Re Rf Rg Rh Rn Ru Sb Sc Se Sg Si Sm Sn Sr Ta Tb Tc Te Th Ti Tl Tm Xe Yb Zn Zr.
Using letters no more than once, I have written as many as possible around a circle such that, if you look at any adjacent pair of letters, then reading them clockwise they are one of the above elements. How many letters have I written?
This brings the total number of Enigmas on the site to 439, which is just over 25% of all published Enigmas – phew! (25.03% to be (more) precise).