How to quickly filter non-1 1 digit phone numbers?

Use function filtering to quickly filter phone numbers that are not 1 1 numbers. Enter the function formula =LEN(A2) in the cell on the right, and the number of digits will appear after the drop-down filling. Then sort the columns in ascending and descending order, and you can intuitively see that the data either shows the phone number of 1 1 digit or the missing phone number.