To text or not to text

Okay, so I've got a friend that texts all the time. A couple of weeks ago she taught me how to do it. A week later she sends me one asking what time we are meeting that night. I think, "I can do this, it's only 3 numbers". So I get all ready, I get to the message box and I start. "53" no zero. My zero key only changes from upper to lower case. I takes me forever but I cancel the text because I couldn't find a delete key. Then I start over and I think "I'll just use the letter o" So I start "53o" But that isn't right either. Still unable to find a delete key I cancel this message as well. Now I'm thinking "I'll just spell it out" I start a new message "five" but when I use my arrow key to move to a new word the phone adds a "s" to the end of five! After starting and cancelling a couple more times with the same results, I give up, call her and leave a voice message "five thirty!" (At five thirty she showed me how to find my 1 and my 0, and punctuation, and how to move to the next word without the phone adding letters.)