In the southern hemisphere, UTM zones have the equator starting at 10,000,000m and descending downward to the S pole to avoid negative numbers, which is why it is important that the north versus south is specified properly, for example UTM zone 18N and UTM zone 18S both have a point 500,000 by 5,000,000 they just differ by a tiny difference of 10,000,000 unless the correct hemisphere is specified