You can't be sure that Facebook doesn't have your number unless you have never given your phone number to anyone who uses Facebook and has your name and phone n

You can't be sure that Facebook doesn't have your number unless you have never given your phone number to anyone who uses Facebook and has your name and phone number. They could be friends, co-workers, relatives, delivery people, cab drivers and many other service providers. One of them shares their address book with Facebook and it knows. A few of them share their address books with Facebook and it's reasonably sure what your number is (names can be fuzzy matched to your profile).