Hi Pete,
When creating the text label, you can format it using LabTalk numeric formatting options, such as:
text.text$="IC50 = $(value, .4)"; // 4 decimal places
text.text$="IC50 = $(value, *3)"; // 3 significant digits
text.text$="IC50 = $(value, E%4.2f)"; // scientific notation
Easwar
OriginLab