Grades 1–12 · Maths
a/b + c/d = (ad + bc) / (bd)
a/b − c/d = (ad − bc) / (bd)
(a/b) × (c/d) = (ac)/(bd)
a/b ÷ c/d = a/b × d/c
mixed number: a b/c = (ac + b)/c
× 10 → shift decimal right 1 place
× 100 → shift decimal right 2 places
÷ 10 → shift decimal left 1 place
to convert fraction → decimal: divide top by bottom
substitution: replace variable with value
like terms: ax + bx = (a+b)x
ax + b = c → x = (c−b)/a
a(b + c) = ab + ac
y = mx + b
gradient m = (y₂−y₁)/(x₂−x₁)
Sum of angles in triangle = 180°
Sum of angles in quadrilateral = 360°
Vertically opposite angles are equal
Co-interior angles: a + b = 180°
Area of circle = πr²
Area of triangle = (1/2) × b × h
Volume of rectangular prism = l × w × h
Volume of triangular prism = (1/2 × b × h) × l
rate = quantity / time
proportion: a/b = c/d → ad = bc
Mean = Σx / n
IQR = Q3 − Q1
P(event) = favourable outcomes / total outcomes
P(not A) = 1 − P(A)
P(A and B) = P(A) × P(B) [independent]
