Hi there. This post is about math memory. As one learns more math (at the high school & university level) you tend to forget the topics that you do not use very often. In addition, those who do not use math after school or on the job, it is very easy to forget the mathematics you have learned from school. Regardless of your credentials in mathematics, there are some things that you don't use, don't remember or did not even learn/know.
This post goes over the type of things you can forget from mathematics along with a section on doing review to get your math memory back.
(One follow up post of this would be expectations of math tutors and math teachers.)

Topics
- Not Knowing Certain Unit Conversions
- Forgetting Certain Formulas
- Forgetting Certain Topics & Algebra Techniques
- You Can Relearn & Remember Through Review
Not Knowing Certain Unit Conversions
Forgetting certain unit conversions is not too bad. Here in Canada, we deal with metres, centimetres, kilometres and not so much in inches and kilometres. Not knowing that 12 inches is 1 foot or not knowing that 1 mile is 1.609 kilometres (in Canada) is not really a deal breaker.
Here are some other unit conversions that you may have forgotten or maybe never heard of:
- 1 fortnight = 2 weeks
- One hectare = 10 000 square metres
- One quart = 4 cups
- One ounce = 28.3495 grams
- One tonne = 1000 kilograms

Forgetting Certain Formulas
As one learns a lot of mathematics, there are more and more formulas to remember. The one challenge is memorizing some of these formulas. Additional challenges with formulas include knowing when to use it and how to use them.
Here is a sample list of formulas (with links):
- Volume Of A Sphere
- Area Of A Triangle
- Area Of A Circle
- The Quadratic Formula
- Midpoint Of A Line
- Distance Formula Between Two Points
- Pythagorean Theorem
- Integration By Parts Formula
- Trigonometric Ratios (SOH CAH TOA)
- Calculus Derivatives
- Linear Algebra Formulas
- Probability Distributions
- Arithmetic & Geometric Sequences & Series Formulas

Forgetting Certain Topics & Algebra Techniques
Forgetting certain topics and algebra techniques from however many years ago is normal. A lot of people can get lost in the algebra details to the point where they forget certain details, and (big-picture) concepts in mathematics.
Here's a list of things you can forget from mathematics.
- Greatest Common Factors & Least Common Multiples
- Prime Factorization
- Long Division
- The Number Of Symmetry Lines In A Polygon
- Complementary & Supplementary Angles
- Completing The Square Algebra Technique
- Graphing Various Math Functions
- Calculus Limits
- Long Division
- Row Reducing A Matrix
- Knowing What Median, Mode and Mean Are
- Z-Score Table Usage From A Normal Distribution

You Can Relearn & Remember Through Review
Despite the long lists from the previous sections, the good news is that you can relearn mathematics through review. Whether you are a math tutor, math teacher, math student or a practitioner you can always review your mathematics. With the abundance or (online) resources out there such as Youtube, websites, online tutoring and such, mathematics learning is more accessible than ten years ago.
For some people, review may not take long as the material looks very familiar. Sometimes the math review is more enjoyable than learning it the first time back in school (where the teacher might have been "bad"). Just like how you learned math (or anything) the first time around, all it takes is focus and good practice.

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