Nudge

Nudging moves objects by small increments.

If you pick up an object you can nudge its position using the numeric keypad. The NumLock key must be on for this to work.

You can pick up a selected object by clicking its reference point, but it is better to use Ctrl + Num 5. Ctrl + Num 5 will pick up the object without any possibility of you accidentally dragging the object.

Use 4 and 6 to move the object along the X Axis.

Use 8 and 2 to move the object along the Y Axis.

Each time you tap a key the object will move a small amount in the associated direction.  Holding down the Shift key will cause the distance moved to be significantly greater.
You can drop a selected object by clicking its reference point, but it is better to use Ctrl + Num 5. Ctrl + Num 5 will drop the object without any possibility of you accidentally dragging the object.
The Nudge distance is specified in Options | Program Setup | Advanced Preferences