Math & Education

How to calculate perimeter: add up all the sides. Formulas for rectangles, squares, triangles, and circles, with examples and perimeter vs area.

How to calculate a ratio: write it with a colon and simplify by dividing by the greatest common factor. Learn to scale ratios and convert to percentages.

How to calculate the average: the mean, median, and mode explained with one worked example, plus when to use each type of average.

How to convert a fraction to a percentage: divide the top by the bottom and multiply by 100. Includes examples, a conversion chart, and the reverse.

Percentage change vs percentage difference: change divides by the original value, difference by the average. See both formulas worked on the same numbers.

Master the three percentage formulas – percentage of a number, X as a percent of Y, and percentage change – with worked examples and mental-math shortcuts.

Learn how to calculate GPA step by step: the 4.0 scale, credit hours, weighted vs unweighted GPA, cumulative GPA, and percentage conversion tables.

The arithmetic is trivial; the answer depends entirely on where you are standing. Tipping norms by country and situation.

The arithmetic is easy; the tactics around it are what cost money. Stacked offers, multi-buys, and how to check a claimed discount in seconds.

Volume formulas for cubes, cylinders, spheres and cones, worked examples, and the cubic-metres-to-litres step people forget.