Re: [math-fun] Concatenate sum of neighbouring digits + iterate

this is perhaps old hat, I don't know...

Take an integer "a" like 962

Sum the first pair of digits: 9+6=14 Sum the next pair: 6+2=8 Concatenate the results: 148 Iterate: 148 --> 512 --> 63 --> 9

Take "b" = 999 999 --> 1818 --> 999

Are there many "looping" integers like 999?

you can find this (and other related problems) discussed here: http://www.stetson.edu/~efriedma/mathmagic/0200.html erich