I love that book! It's by Marilyn Burns, and was part of the Brown Paper Schoolbook series (which had lots of cool titles).
Almost 30 years ago, I was tutoring a junior high student in the summer, and used activities from this book. We filled her mailbox with popcorn and estimated how many popped kernels it would take to fill it.
I thought it was "The secret key to mathematics is pattern." That's what I write on my board every semester, and attribute to her. Maybe she said it both ways.
Warmly,
Sue