Changing Multiple Object Size

This question came up on another forum and I don't think I know how to do this.

Say you have 20  separate circles all the same size (.5 mm X .5mm) on your workspace.

Now, you want to enlarge all those circles to 1.5 X 1.5 mm.

Can this be done simultaneously? Or do they have to be transformed individually?


My mind is a blank.