which data type used for entering the Mobile number for user which use less memory

Answer 1

depends on the number of digits in the mobile number but unsigned or unsigned long should be enough

Answer 2

i would use long instead of int but im unsure if im answering your question right.

Answer 3

4,294,967,295 is max. range of unsigned long so its too short for to store mobile number so its answer should be "unsigned long long int" may be

Answer 4

Or use two numbers