How to fill out a salary range in an online job application?

Most experts will tell you to not say your salary range, try to get the employer to give their range and see if you fit. With todays online job applications, a lot will require you to enter a salary number...with the form not allowing you to proceed to the next step in the application without it. There is no room for a range and a number must be entered in order for you to apply. What should one do in this situation?