"j" を 10回連続して押す実験 (length "jjjjjjjjj") => 9 (length "jjjjjjjjjj") => 10 (length "jjjjjjjj") => 8 (length "jjjjjjjjjj") => 10 "k" を (人差指で)10回連続して押す実験 (length "kkkkkkkkkk") => 10 (length "kkkkkkkkkk") => 10 (length "kkkkkkkkkk") => 10 (length "kkkkkkkkkkk") => 11 あれ?指がちゃったった。裏を見ると、1999年 5月製と書いてある。さすがに限界か。