I have a table like
CONTACT
Name Null Type
This is a function of the way the value is displayed, not what is being stored in the database. The database just stores a numeric float value, and whatever retrieves and displays the data decides how to display that. The exponential value you mention is common for displaying such floating point numbers.
You can have Oracle return a string formatted in a way for display using a function such as to_char, that allows you to set formatting. However, it may make more sense to handle this in whatever program or code is using the database.
Also note that floating point numbers have limited precision, so if you need to get that exact number string back, a float is not the way to go.