Lee Mac's Text Calculator is a good example of using his Parse Numbers function to perform arithmetic operations on text containing numerical data, placing the result of such calculations as an MText object in the drawing, these text objects may be Single-line Text, Multi-line Text, a Dimension, Multileader or Attribute.
If the text of the selected object contains multiple numbers, the user is prompted to choose the number to use in subsequent calculations. After selection, the user is presented with a dialog interface from which an arithmetic operation may be selected or the result of the calculations so far may be placed in the drawing.