Math Abbreviations and Acronyms

GCF, GCD and HCF all refer to the greatest common divisor.

Some entries below are acronyms; others are abbreviations or function names. Meaning can depend on context.

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Mathematics abbreviations and acronyms
Short form	Meaning	Usage
GCF	Greatest common factor	Largest positive integer dividing all given integers.
GCD	Greatest common divisor	Another name for GCF.
HCF	Highest common factor	Another name for GCF.
LCM	Least common multiple	Smallest positive integer divisible by all given nonzero integers.
LCD	Least common denominator	Least common multiple of fraction denominators.
LHS	Left-hand side	Expression to the left of an equals or comparison sign.
RHS	Right-hand side	Expression to the right of an equals or comparison sign.
iff	If and only if	A statement asserting both directions of an implication.
PEMDAS	Parentheses, Exponents, Multiplication/Division, Addition/Subtraction	Multiplication and division share a level; evaluate left to right. Addition and subtraction also share a level.
BODMAS	Brackets, Orders, Division/Multiplication, Addition/Subtraction	An order-of-operations mnemonic; division and multiplication have equal precedence.
PDF	Probability density function	Density for a continuous random variable.
PMF	Probability mass function	Probabilities for a discrete random variable.
CDF	Cumulative distribution function	F(x) = P(X ≤ x).
SD	Standard deviation	A measure of spread, in the original units.
SE	Standard error	Standard deviation of the sampling distribution of an estimator.
CI	Confidence interval	An interval procedure with a stated long-run coverage under its assumptions.
IQR	Interquartile range	Third quartile minus first quartile.
df	Degrees of freedom	A model- or statistic-dependent count of independent information.
ln	Natural logarithm	Logarithm with base e.
log	Logarithm	Its base depends on context; specify the base when ambiguous.
sin	Sine	A trigonometric function.
cos	Cosine	A trigonometric function.
tan	Tangent	sin θ / cos θ where cos θ is nonzero.