I saw that too, since my pronoun 'it' would be inferred to refer back to the noun 'number theory.' Since when I wrote that note I was thinking 'it' referred back to the analysis of Kaprekar numbers, which I didn't think taught much (but see my note about the process being useful in other pursuits). That was why I went back and edited it to illustrate the 'it' I was referring to. Anyway, packets on the far side of the firewall and all that.