Dave
Do you mean Maths Maths, or mental arithmetic ? - slight difference!
You will certainly need quick thinking for the aptitudes at Cranditz
You might like to opt for boning up on Quantum Mechanics - slightly more interesting than Algebra - it was fundamental in putting a man on the Moon and helping people like you buy a cheap PC to get on the internet, despite what Einstein thought.
As a last resort, you could ask your mum to find a creche where they do counting using oranges and apples.
Best of luck !