In the past it used to be quite a common practice: a Head of State, a Queen, King, Prince or Princess or lower level political dignitaries would be on an "official" visit in Singapore and next to numerous events they would come to Jurong Town and plant a tree in this garden.
Located on Jurong Hill it is close to the Jurong Bird Park (a visit is highly recommended!) and the look-out platform provides a nice spot to enjoy the scenic view over Jurong.
How to find the cache:
Step 1: Find the oldest tree (as per placard): which anniversary did the dignitary attend? (A)
Step 2: Find the tree planted by Queen Elisabeth II - how many days did she spend in Singapore? (B)
Step 3: Find the tree planted by a Prime Minister of Japan: On which day (C) in which month (D) during 1977 did he plant it?
Step 4: Find the tree planted by the President of the Senate of Germany's second largest city Hamburg - in which year (E) did he plant it and how many letters does his last name have (F)?
You will find the cache hidden not too far away at
N 01.19.XXX
E103.42.YYY
with XXX = (A /B) - C +D+F
and YYY = E-1500 + D - F
Happy caching!