This cache will take you to the old Thirroul Presbyterian Church, which subsequently formed the Williams Uniting Church.
The last service in the church was held at 8:30am on Sunday morning 17th October, 1999 when the congregation then moved to the Bulli Uniting Church to combine with the Northern Illawarra congregation.
The old church has now been turned into a residence, respect the residents in your caching but you'll just need to gather some information from the plaque outside to continue on with the cache.
At the bottom of the plaque, read what years the Thirroul Presbyterian Church operated here. We'll call these numbers ABCD - EFGH.
To find the next waypoint, you will need to add C(C+D)(C-E) to the South Decimals and subtract E(E-1)G from the East Decimals.
At this point you should find an object and a plaque behind it. On the last line of the plaque there are some numbers. We'll call these I: JK-LM.
To calculate GZ, you will need to add (I+J)(J+L) to the South Decimals and subtract (K-J)(J+L+M) from the East Decimals (from your current waypoint).
GZ should be a very short walk away- watch the traffic!