Adjusting Shapes relative to their size

Rhino Rhino for Mac
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1

Hey self taught user here with a simple question:

Say I have a cube and want to make the X-axis side shorter by 2 inches. Is there a quick way to do that if I dont know the full length of the X side?

Currently I would have to use >Distance, measure the side, and then >Scale1D to adjust with mental math.

Thank you!

2

As i read it you could Sub-Select and use the gumball to enter the distance in the X direction.