18 tools
Online calculators
Percentages, interest, discounts, loans, statistics and everyday maths, worked out in your browser.
Everyday calculators that show their working: percentages and percentage change, discounts, adding or removing VAT, compound and simple interest, savings goals, pay per hour, splitting a bill, fuel for a trip, GPA and exam marks, and the maths behind ratios, fractions, prime numbers, statistics and quadratic equations. Each page explains the formula in words with worked examples, so you can check the answer by hand and use it in homework, a quotation or a budget. They run in your browser with nothing to sign up for.
Percentages, discounts and VAT
Percentages of a number, percentage change, discounts and sale prices, and adding or removing VAT, with the working shown.
Interest, savings and pay
Compound and simple interest, how long a savings goal takes, and what a salary works out to per hour.
Everyday costs
Split a bill with a tip, and work out what a trip costs in fuel.
Marks and grades
A GPA on the scales Sri Lankan universities use, and exam marks as a total, percentage and average.
Maths and statistics
Ratios, fractions, greatest common divisors and least common multiples, prime numbers, statistics and quadratic equations, each with the steps written out.