def clickGO(event):
x = entryvalue.get()
if fNumSystem == 2:
answer = Label(root, text=ConvertFromBin(x, sNumSystem))
answer.grid(row=7, column=3)
elif fNumSystem == 8:
answer = Label(root, text=ConvertFromOct(x, sNumSystem))
answer.grid(row=7, column=3)
elif fNumSystem == 10:
answer = Label(root, text=ConvertFromDec (x, sNumSystem))
answer.grid(row=7, column=3)
elif fNumSystem == 16:
answer = Label(root, text=ConvertFromHex(x, sNumSystem))
answer.grid(row=7, column=3)
вот в этом фрагменте