Expert guides for parents, students and math enthusiasts. Algebra to Olympiads — we've got you covered.
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The goal was never to make kids faster at math — it was to make them fall in love with it. Speed is a byproduct of genuine understanding.

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Variables, equations, and the language of math

Types of functions are grouped by mapping, degree, range and family. Each type below has its definition, conditions, a graph or mapping diagram and a checked example, with practice answers at the end.

Linear equations in one variable can be written in the form ax + b = 0. If a ≠ 0 there is exactly one solution, x = -b/a; if a = 0, there is no solution (b ≠ 0) or every number is a solution (b = 0).
Roots in polynomial expressions are the values of x that make the polynomial equal zero, so a root of P(x) is any x with P(x) = 0. A number r is a root exactly when (x - r) is a factor, and by the Fundamental Theorem of Algebra a degree-n polynomial has exactly n roots when you count multiplicity and allow complex numbers.
Shapes, proofs, and spatial thinking

Collinear vectors are vectors that lie along the same line — which means one is always a scalar multiple of the other, a = k,b. This article covers the three tests for collinearity (scalar multiple, equal coordinate ratios, zero cross product), how collinear differs from parallel and coplanar, and worked examples.

Rotational symmetry means a shape maps exactly onto itself when turned about its centre by some angle smaller than a full turn. The order counts how many times it matches in one 360° rotation, and the angle of rotation is 360°/(order); this guide gives the definitions, six worked examples, and the traps that produce a wrong order.

A transversal is a line that crosses two or more other lines at distinct points. When the transversal crosses two parallel lines, exactly 8 angles form — grouped into four named pair-relationships (corresponding, alternate interior, alternate exterior, co-interior).
Angles, waves, and circular harmony
The value of tan 7π/6 is exactly 1/(√3), or in rationalised form (√3)/3, which is about 0.5774. This article shows why the answer is positive (the angle lands in the third quadrant), how the reference angle (π)/6 produces the value, and how the unit circle confirms it, with a tangent table, worked examples, and the mistakes to sidestep.
Sin A cos B equals 1/2[sin(A+B) + sin(A-B)], a product-to-sum identity that turns a product of a sine and a cosine into a sum of two sines. This article covers the formula, its derivation from the angle-sum and angle-difference identities, six worked examples, the mistakes students make, and why the identity matters for integration.
The sin double angle formula is sin 2x = 2sin x cos x, which rewrites the sine of a doubled angle using the sine and cosine of the original angle. This article covers the formula, its derivation from the angle-sum identity, the tangent form, six worked examples, the mistakes to avoid, and where doubling an angle actually matters.
Raising confident, curious young mathematicians
Every essential formula, explained and derived
The semicircle formulas are: area = 1/2π r², arc length = π r, perimeter = π r + 2r = r(π + 2), and diameter = 2r. This article gives every semicircle formula, why each comes from the full-circle analogue, three worked examples spanning Quick to Stretch, and the single most common mistake students make — forgetting the diameter when computing perimeter.

The mean is the average of all values (Σx / n), the median is the middle value when data is ordered, and the mode is the value that appears most often. Use the mean for symmetric data, the median for skewed data with outliers, and the mode for categorical data. For moderately skewed distributions, the three are linked by Karl Pearson's empirical relation: Mode = 3 Median − 2 Mean.
The percentile formula tells you where a value stands in a dataset: P = (number of values below x)/N × 100. This article covers both directions — finding the percentile of a value, and finding the value at a given percentile — with worked examples, the percentile-versus-percentage distinction, and the mistakes that trip students up.
Crystal-clear definitions with worked examples

An irrational number is a real number that cannot be written as a ratio of two integers (p/q form), and its decimal expansion never terminates and never repeats. Common examples include √2, π, e, and the golden ratio φ.

An integer is a whole number - positive, negative, or zero - with no fractional or decimal part, written as the set ℤ = {..., −3, −2, −1, 0, 1, 2, 3, ...}. Integers follow closure, commutative, associative, distributive, identity, and additive inverse properties, and form the foundation for arithmetic, the number line, and all rational numbers.
The radius of a circle is the distance from its centre to any point on the boundary, and it is exactly half the diameter. This article covers the definition, the three formulas for finding the radius, how it ties to the circle equation, six worked examples, and the common mistakes.
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