If your script is using Set field to "enter the number" this change is happening at the data level, not the interface level and no script triggers are tripped. If you used Insert Calculated result, this would trip the trigger. But you could also stay with Set field and just follow up with a Perform Script call to perform the trigger controlled script.
But I'd also consider using a calculation field to compute this value instead of a script.
I have a couple calculation fields in there already and it slows things down. I did not think to use the script that is triggered, to trigger it... That is a good idea. Ill do that.