Easier to count, really. It's not like they all didn't have the same name, after all.
The Doctor walked next to Rose, taking her hand silently in his and giving it a little squeeze. Didn't want her to worry about that. Not in the least because he and Donna would likely tear each other's heads off.
"So, you were born from his DNA... fantastic! What a remarkable machine. How old were you?" He wondered if he popped in and out during her life, or only came back after she was fully grown.