Question

if the ones digit of a number is 7 and 10 digit is 5 the number is ​

Answer 1

In the United States and Canada, ten-digit dialing is the practice of including the area code of a telephone number when dialing to initiate a telephone call. When necessary, a ten-digit number may be prefixed with the trunk code 1, which is referred to as 1+10-digit dialing or national format.