Here is a V2 and V3 compatible Python instruction to achieve this
"{}_{:04d}".format('test', 35)

So that a Python script could look something like this:

dialog = poser.Dialog()
txt_dlg = poser.DialogTextEntry(dialog, question)
if txt_dlg.Show():
    base_file_name = txt_dlg.Text()
    for i in range(number_of_iterations):
        full_file_name = "{}_{:04d}".format(base_fiule_name, i)

𝒫𝒽𝓎𝓁

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