The foundation of all mathematics

Your arithmetic journey

Six branches, walked in order — each one makes the next easier. Finish a branch to unlock the next stretch of the path.

6 branches21+ topics∞ practice

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Skill Sparks

Interactive playgrounds — poke, drag and break arithmetic ideas to see how they work.

1
Natural NumbersThe counting numbers
In progress
The numbers you count with (1, 2, 3…) — ordering, comparing and the number line.
Not startedStart →
2
IntegersPositives, negatives & zero
Up next
The whole-number line extended into the negatives — and why minus times minus is plus.
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FractionsParts of a whole
Locked
Numerators, denominators, and making peace with common denominators.
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Rational NumbersRatios & quotients
Locked
Any number that is a ratio of two integers — fractions all grown up.
Not startedStart →
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Irrational NumbersNon-terminating & non-repeating
Locked
Roots, Pi, and the numbers no fraction can catch.
Not startedStart →
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LCMLeast Common Multiple
Locked
The smallest common multiple linking numbers together.
Not startedStart →
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HCFHighest Common Factor
Locked
The greatest divisor that fits perfectly into two or more numbers.
Not startedStart →
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DecimalsTenths & beyond
Locked
Place value past the point — reading, comparing and computing with decimals.
Coming soon
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PercentagesPer hundred
Locked
Discounts, interest and growth — fractions dressed for real life.
Coming soon

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Not sure where you stand? A 10-minute discovery test places you on the path automatically.