What is the mechanism to instruct the script engine to ignore the first % in the %NW parts of the string?

The instruction:
Let>Text1=Common words: %NW{%Fip%}0 - %NW{%Fip%}3

results in:
%NW{%Fip%}0 - %NW{2}3

instead of the desired:
%NW{2}0 - %NW{2}3

Regards