How can we show Last N Days of Data in Report

I have come across one requirement from one of my Blog Followers,

He wants to see the data for Last N Days ( Here N is Parameter, He wants to pass the Value through the Parameter)

Solution:

1) Create a parameter using t he "Integer" as the Data Type (Since we can type No. of Days of data want to see in the Report).

2) Then Create a Calculated Field like below image.

3) Then Drag the Date Field, Calculated field which was created in above step.

4) Then data will show like below image.

5) Report will show the data for Last N Days, shows nulls for rest of the Days. ( Since did not provide else part our condition)

6) Want to show Non-Null values in the Report, then drag the above calculated field into filters shelf, then click on "All Values" then select "Non-null values" as like below image.

Now Report will show data which does not have  the Nulls.