Same thing are "fourt-tuhn", but pull your thumb in. In decimal it equals 37, or 32 for my left thumb, and 4 and 1 for my right middle finger and thumb. Again, in Base Thirty-Two (or duotrigesimal, or dtg), it is "15".
So: 15 dtg = 37 decimal! SORRY I just realized I had gotten this WRONG when I first posted it! I'm mortified! ;)