This morning I was so out of it that I couldn't hear when my temp was done. The first two times it read around 98.02, but I wasn't sure if the thermometer was done because I didn't hear it go off (I just realized it had been a while so I checked it to make sure I had actually turned it on), so the third time I heard it go off, but it read 97.9....so which one do I use? The one that I heard go off, or the first reading that I wasn't sure about?