Math Formula Encyclopedia
Search, understand, and use formulas across arithmetic, algebra, geometry, trigonometry, calculus, statistics, finance, science, engineering, and everyday math.
134 formulas10 subjectsExamples + variables
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8 matching formulas
Arithmetic
Percentage of a Number
P = (r/100) × N
Find a percentage of a quantity.
Open formula →ArithmeticPercentage Change
% change = ((new − old) / old) × 100
Measures relative increase or decrease from an original value.
Open formula →ArithmeticAverage (Arithmetic Mean)
x̄ = (x₁ + x₂ + … + xₙ) / n
Adds all values and divides by the count.
Open formula →ArithmeticWeighted Average
x̄w = Σ(wᵢxᵢ) / Σwᵢ
Average in which values contribute according to assigned weights.
Open formula →ArithmeticRatio
a : b = a/b
Compares two quantities by division.
Open formula →ArithmeticProportion Cross Product
a/b = c/d ⇒ ad = bc
Solves equivalent ratios by equating cross products.
Open formula →ArithmeticSimple Interest
I = Prt
Calculates interest without compounding.
Open formula →ArithmeticCompound Amount
A = P(1 + r/n)^(nt)
Future value with periodic compounding.
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