On page 28, question 8, when I looked at the solutions, the number 1 was plugged in to solve the problem…

On page 28, question 8, when I looked at the solutions, the number 1 was plugged in to solve the problem. However, on the beginning of the book the author said to never plug 0 and 1…Anyhow, my question is, if never plugging 1 is suggested, how did you know that plugging 1 in would work in your favor for the question(btw I got it right but I didn’t plug 1 in, I thought of other numbers but it did take me longer to figure out the numbers that’d add up to 11)