When they hire you as a cashier at McDonalds, your math is useless. All you need is learn to ask "do you want fries with that?"
If you wanna get (and keep) a developer job, learn development. Leetcode is just an example, learn algorithms and data structures and patterns and languages. Math is literally the least useful thing to learn in 99.98% of real programming jobs.
This skill isn't needed anymore because fries are included in most meals.