Iphone6 A contacts have multiple numbers. How can he find out which number he sent the text message?

First, click on the short message,

Then, click on the contact information in the upper right corner, which contains all the numbers of this person, and the blue one is the number he sent.

Place the text message between all the numbers of the contacts in the dialog box.

(The contact person and telephone number are displayed at the top of the SMS interface, and the number displayed here is the number of the last communication. Clicking on the contact photo area remains unchanged, but clicking on the contact name and number area will require you to select the contact number and send a message, so as to switch between multiple numbers.