Basic Math
Because doing this all by hand is for people living before computers were awesome.
Quadratic Formula
Given
\(ax^2+bx+c=0 \)
solve for x : $$x = \frac {-b \pm \sqrt {b^2 - 4ac}}{2a}$$
Distance Formula
Given two points \((x_1,y_1)\) and \((x_2,y_2)\)
solve for distance between them :
$$\sqrt{(x_1 - x_2)^2 + (y_1 - y_2)^2}$$
Common Factors
Greatest Common Denominator (GCD) and Least Common Multiple (LCM)