Increasing the size of Mesh Grid

I am following this tutorial for crearing landscape.

In the Step Creating the Canvas it is mentioned to start with a grid 100x100 and scale it by a factor of 20. I know of the Scale button in Tools and did it but not getting a grid as shown. I understood that i am not in the right track. What i did is just scaling not increasing the size, this is obvious by checking the spacing between the lines of the mesh grid.

Can you plaese tell me how to create a 100x100 grid in blender 2.74 version.

Shift+A / Add / Mesh / Grid
Look in toolshelf or press F6
Set the X and Y subdivisions to 101
If you want to scale it by x20 then select the mesh and S 20