1. **Addition**: a + b = c

2. Subtraction: a – b = c

3. Multiplication: a x b = c

4. **Division**: a ÷ b = c

5. Exponents: a^n = c

6. Square root: √a = b

7. Order of operations: PEMDAS (Parentheses, Exponents, Multiplication and Division, Addition and Subtraction)

8. Fractions: a/b

9. Decimals: 0.1, 0.2, 0.3, etc.

10. Percentages: a% = a/100

11. Ratios: a:b

12. Proportions: a/b = c/d

13. Area of a rectangle: A = l x w

14. Perimeter of a rectangle: P = 2l + 2w

15. Area of a triangle: A = 1/2bh

16. Perimeter of a triangle: P = a + b + c

17. Circumference of a circle: C = 2πr

18. Area of a circle: A = πr^2

19. Volume of a cube: V = s^3

20. Volume of a rectangular prism: V = l x w x h

21. Volume of a cylinder: V = πr^2h

22. Pythagorean theorem: a^2 + b^2 = c^2

23. Mean: (a + b + c + … + n) / n

24. Median: the middle number in a set of numbers

25. Mode: the number that appears most frequently in a set of numbers.