There’s a common saying that “practice makes perfect”, and that is especially true for Math.

Math especially has a certain thing where there are “trends” of questions, meaning that certain kinds of questions will be repeated over and over again (with different numbers, of course).

If you keep practicing, especially on past year O level Math papers, you’ll eventually be able to spot the trends (they might be different each year) and repeat the method to do those questions in your own year’s O level Math paper.