Keywords:
Molecular Weight Ml. Wt. ChemDraw brackets
Details:
Using brackets (curly brace or parenthesis or square) you can isolate a segment of the structure (eg. poly(ethylene glycol) derivative) and build an oligomer with parameterized units and override the molecular weight.
You will find additional information in the ChemDraw Help/User Manual (Help > Contents). Search for "Molecular Weight Override and Derived Calculations"