When we discussed closed and open intervals In the 7th-grade math class I teach, I stumbled a bit when it came to talking about the possibility that 0.99999. . . is the edge of an open interval. I told the students that for technical reasons we can't say that, and 0.99999... = 1, but that to explain why to them would be too hard. My student Job Currell asked his older brother Isaac though, and found out, and we talked about it in class. That was good, but I thought I'd better write up a handout to explain this weirdness. It's something I'd never heard of myself before I was in my 50's, when Professor Christopher Connell told me about it. The handout became this Substack article.
Why 0.9999 . . . Equals 1.0000 . . .
Why 0.9999 . . . Equals 1.0000 . . .
Why 0.9999 . . . Equals 1.0000 . . .
When we discussed closed and open intervals In the 7th-grade math class I teach, I stumbled a bit when it came to talking about the possibility that 0.99999. . . is the edge of an open interval. I told the students that for technical reasons we can't say that, and 0.99999... = 1, but that to explain why to them would be too hard. My student Job Currell asked his older brother Isaac though, and found out, and we talked about it in class. That was good, but I thought I'd better write up a handout to explain this weirdness. It's something I'd never heard of myself before I was in my 50's, when Professor Christopher Connell told me about it. The handout became this Substack article.