Grep the only number which is enclosed in doublequotes (Newbie)?

[Srinu]

For example my file contains following content,

rder"19986598"
order"19984512"
orders"123456789"
str"23456789"
123456789
"12345678"
"23456789"

now i need to grep the number which is in double quotes.

I need the number enclosed wit in double quotes.

ex: if my file contains "23456789" now i need it as 23456789.


Thanks in advance
in UNIX !!