Sometimes, neither mouse nor keyboard methods of transforming are quite up to the task because you know exactly how far (or to what point) you want to move your objects or by what angle to rotate them. Inkscape allows you to specify exact numeric values for transforming selection.
There are two places where this can be done. One is the controls bar of the Selector tool:
Here, the X and Y values specify the position of the selection and W and H specify its width and height. Not only do these values automatically update when you select and deselect objects or move or scale the selection, but they also allow you to type any values to have the selection moved or scaled correspondingly.
Note
The coordinate origin for the X and Y values is in the top-left corner of the page (3.4.3 Page Size).
After typing a value in the field, press 
to activate it, or press 
to activate it and move to the next field. To jump to the first field from the keyboard, press 
.
To the right of the editable fields, there’s a drop-down menu for selecting the unit in which the values are expressed. Inkscape supports a number of units, including in (inches), pt (points, each point being 1/72 of an inch), mm (millimeters), and cm (centimeters). The default unit is px (SVG pixel, A.6 Coordinates and Units).
One of the most useful units is the % (percent). It allows you to scale an object not to some absolute size but as a percentage relative to its current size. For example, to scale selection to 1.5 times its size, switch the unit to % and type 150 in the W and H fields (if you click the lock button between them, setting only one of these fields to 200 will be enough).