I somehow managed to make it through middle school with 3rd grade Math, but now that I'll start high school I can't fail a class. If I fail, I can't join a student exchange program. I can barely do the basics and even struggle at division. How can I learn Maths quick?
Most Helpful Guy
It would seem that many people have difficulty with math. However there is also evidence I believe, that in an appropriately supportive environment, most people are easily capable of obtaining significantly improved math skills. A lack of confidence would often seem part of the problem.
On a general level, the best advice I can give off the top of my head is of course to study often and early, and to perhaps consider getting a tutor to aid you, as well as making use of online resources. Beyond that some specific points which might be worth considering (and I apologize if any of this is overly involved):
mnemonics can be very helpful, such as the phrase 'please excuse my dear aunt sally' which is used to remember the order of operations. Phrases like this and other memory aids are good to learn early.
The basic multiplication tables should pretty much be brute force memorized. You don't need to know every number on it, but the better you know it the easier it will be to do simple multiplication and division quickly.
Theorems can be very helpful if you understand them. A personal favorite of mine is the fundamental theorem of arithmetic, which says that all numbers represent the product of a unique set of prime number factors. Knowing this, you can use various tricks to try to determine the prime number factors of a number, which could let you more easily divide or multiply. As an example, numbers which have 5 as a prime number factor end in 0 or 5, numbers which have 3 as a factor have digits which sum to a multiple of 3.
15 ends in a 5 and 1+5 = 6 which is divisible by 3. So the prime number factors of 15 are 5 and 3. Any other number that has 3 and 5 as prime number factors will be evenly divisible by 15 also as they share the same prime number factors. For instance 405 ends in a five and 4+0+5=9 which is divisible by 3, thus 405 is evenly divisible by 15. The same for 10110 or 1011002010, both are evenly divisible by 15 which can be determined in a second or two simply using addition.
The better you understand how numbers work, the better you will be able to manipulate them. And the less energy it might take to learn it.1
Most Helpful Girl
The teacher should help you, it's their job to teach you. It's what they get paid for and it's why you are there. Go and speak to them, tell them you do not want to fail but your previous teachers have failed you and you are not at the level you ought to be.0