The mental maths was first, and it was to answer as many questions as you can in 15 minutes. There were 25 questions, and there were rumours in the waiting room that 15 correct answers was the pass mark, so you needed to work to at least a question per minute to pass. For the other questions, you had a lot more time, and they had real-world scenarios, such as calculating fuel consumption, etc.
The competency side of things in the interview are just putting your life experience into relevant examples.
I struggled for the motivation side of things, because I applied on a whim, and didn't do any preparation, which came back to bite me. You know what they say, Prior Planning and Preparation Prevents P*** Poor Performance, so prepare well, that's all it takes!
For the motivation side of things I was told that they like to see that you're 110% into flying, so they love to see that you fly as a hobby, and or you've taken steps already to become a commercial pilot. At the time I didn't have any flying experience (I do now), so they didn't like it, and they asked very difficult questions, such as "If you've never flown, how do you know you will like a career as an airline pilot?", which is very difficult to answer, so they took this as my motivation was lacking. It also looks bad when a lot of the other applicants have PPLs and other things, so they only way to get out of it is to get some flying experience.
Also, learn every fact and figure about the course, such as where, when, and for how long, and do this by heart. Prepare an inspirational story about why you want to pursue the career, as they may ask you that, and don't be scared of embarrassing yourself. The more extravagant and memorable your story, the more they will remember it! If you get in, who cares, it's not what it says in the scorebook.
