Royal V Heath's phone number trick

Write your phone number on a sheet of paper.
Hide this number so that I can't see it !

Now calculate :
give me the sum of the first and of the second digits, then the sum of the second and the third digits, then the sum of the third and of the fourth digit and so on until you get to the tenth and last digit.

Finally give me the sum of the second and the last digit.

first plus second,
second plus third,
third plus fourth,
fourth plus fifth,
fifth plus sixth,

sixth plus seventh,
seventh plus eighth,
eighth plus ninth,
ninth plus tenth,
second plus tenth.

Let's think !
Here's your phone number

Royal V.Heath's phone number trick.