Percentages of what? Groups, different bases and rate ratios
Decode percentages with different denominators: shares, rates, counts, comparisons between groups A and B, and an interactive laboratory with editable examples.
ReadMathematics
Articles by topic
Clear, organized learning paths that build strong foundations in mathematics and computer science.
Arithmetic
Word problems without equations: 13 arithmetic methods and 36 worked problems
A toolkit for primary school: 13 strategies, 36 word problems, concrete examples and step-by-step solutions to reveal only after trying for yourself.
ReadWorking together: three problems and their formulas
From individual times to working together, then the reverse journey: a difference or a ratio between times. Parametric systems, reduction of the third case to the second and worked examples.
ReadFour or five numbers, one hundred targets: find the best group
An arithmetic lab with 4 or 5 numbers, targets from 1 to 100 and exact step-by-step solutions.
ReadThe equal-parts method: 25 illustrated problems from primary to lower secondary school
Solve word problems using equal parts and bar models: clear explanations, 25 progressive exercises, diagrams and worked solutions revealed with a click.
ReadFinancial mathematics: mortgages, payments and amortization schedules
From interest rates to payments: worked examples and tables comparing level-payment, equal-principal and bullet repayment methods.
ReadUniversity entrance tests: mathematics papers and resources
Science Faculty papers and the ESAT guide, with four separate quizzes, booklets and explanations.
ReadINVALSI grade-10 mathematics papers: quizzes by year and worked solutions
Four separate quizzes for the 2012–13, 2013–14, 2014–15 and 2016–17 papers, with booklets and marking guides.
ReadDecimal odds and percentages: from stake to overround
Why does 1÷1.9 equal 52.63%? From stake and net profit to implied probabilities, overround and theoretical payout.
ReadRepeated digits: five 5s and six 6s
Forty repeated-digit challenges, strategies for building expressions and an interactive laboratory.
ReadNumber systems: conversions and games
From base x to base 10, base 10 to base y and between two bases: examples, six cards and an interactive lab.
ReadMathematics entrance test: topics and online quiz
A short guide to the 45-question first-year secondary-school entrance test, with a link to the quiz and its review.
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