Exponential Growth and Decay: Formula, Doubling Time and Half-Life
Understand exponential growth and decay, use A = A₀(1 + r)ᵗ, and find doubling times and half-lives with logarithms. Worked examples.
Author: <span>math_person</span>
Percentages When Shopping: Discounts, Tax and Tips
Work out sale prices, stacked discounts, VAT or sales tax (adding and removing it) and tips quickly, with the multiplier method.
Confidence Intervals Explained (Without the Jargon)
What a 95% confidence interval really means, how to calculate one from a sample mean, and how sample size changes the margin of error.
Complex Numbers for Beginners: i, Arithmetic and the Argand Diagram
What i = √−1 means, how to add, multiply and divide complex numbers, and how modulus, argument and the Argand diagram work.
Completing the Square and Vertex Form, Step by Step
Learn how to complete the square to write a quadratic in vertex form a(x − h)² + k, find the vertex, and see why it matters for graphs.
Box Plots and Quartiles: Five-Number Summary and Outliers
How to find quartiles and the interquartile range, draw a box-and-whisker plot, and spot outliers with the 1.5 × IQR rule.
The Binomial Distribution Explained Step by Step
When to use the binomial distribution, the formula for exactly k successes, at-most and at-least probabilities, and the mean and standard deviation.
Binary and Hexadecimal Explained: Converting Number Bases
How place value works in binary and hexadecimal, and how to convert between decimal, binary and hex step by step.
What Is the Discriminant? Reading a Quadratic at a Glance
The discriminant b² − 4ac tells you how many roots a quadratic has and what kind they are. Learn to use it with clear examples.
Volume and Surface Area: The Formulas You Actually Need
Volume and surface area formulas for cubes, cuboids, cylinders, cones, spheres and pyramids, with worked examples and the one-third rule explained.