The approved calculator for all subjects is the Casio FX82 (any suffix). No equivalent model of calculator is allowed.
For a small number of subjects (mostly those requiring complex number calculations) the Casio FX100 (any suffix) will also be allowed. If that’s the case for one of your subjects, your Subject Coordinator will let you know at the start of the teaching period.
Read the FAQ about calculators in examinations.
You can buy Casio calculators from the University Co-Op Bookshop, or from OfficeWorks stores.