Why do I have to learn THIS (Math)?
There are lots of things to learn in this world! But some things just don't make sense on why you should learn them - it's nothing that you're going to do, right? You'd be surprised! Let's take a few occupations and careents and see which subjects you'd need to know!
Mathematics
We most often hear student say that they'll "never use this" talking about Math. Math is an interesting topic - while you may not use a particular lesson in Math during your career, they math you will likely be working on is actually based on topics you learned during your school years! For example - there are no many jobs out there that have someone sitting at a desk, adding and subtracting fractions. However, in order to be a Chemist or Engineer (along with many other careers), you'd have to know how to perform those calculations.
Let's take a look at some jobs that you may not expect to need to know much math:

Garbage Man (Sanitation Worker)
During your years of keeping the streets and people's curbsides free of trash, you'll need to be able to calculate the mass, volume, and weight of the trash. If later you become a manager or supervisor, you will also need math to calculate finances and budgets!
Sports Player (Football, Baseball, Basketball, etc.)
You're going to make $10,000,000.00 per year (that's ten-million!), so you won't need to worry about math, right? What if your sports agent tells you that you can either pay him 10% of your total contract price upfront, or 2% per year over the length of the contract, with 1.25% interest per year? You'll need to make sure you're not being ripped off!
Law Enforcement (Police Officer, Investigator) 
A police officer needs math in order to judge times and distances for himself and others he may be following. Often times, what he comes up with in regards to the question of "when will you see the car crossing if you're 10 miles away" is a very close estimation - which requires basic knowledge of how to use formuals, along with quick thinking and ability to perform calculations in your head.
Investigators and Officers may also need to determine the speed of a car by the length of the skid marks, trajectory of projectiles (where did the bullet originate from), and other calculations. Depending on your exact career and job duties, you may need to be very precise with your calculations, or very quick with a good estimation.
As you can see, even careers you may not have thought involving the use of mathemati