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
AllAlgebra 16Arithmetic 8Calculus 15Everyday Math & Conversions 7Finance & Business 9Geometry 28Number Theory & Sequences 8Science & Engineering 16Statistics & Probability 16Trigonometry 11
8 matching formulas
Number Theory & Sequences
Arithmetic Sequence Term
aₙ = a₁ + (n−1)d
Nth term of an arithmetic sequence.
Open formula →Number Theory & SequencesArithmetic Series Sum
Sₙ = n(a₁+aₙ)/2
Sum of an arithmetic series.
Open formula →Number Theory & SequencesGeometric Sequence Term
aₙ = a₁r^(n−1)
Nth term of a geometric sequence.
Open formula →Number Theory & SequencesFinite Geometric Series
Sₙ = a₁(1−r^n)/(1−r)
Sum of first n terms of a geometric series.
Open formula →Number Theory & SequencesInfinite Geometric Series
S = a₁/(1−r)
Sum of a convergent infinite geometric series.
Open formula →Number Theory & SequencesEuclidean Algorithm
gcd(a,b)=gcd(b,a mod b)
Repeatedly reduces a greatest-common-divisor problem.
Open formula →Number Theory & SequencesEuler Totient for Prime
φ(p)=p−1
Counts positive integers up to p that are coprime to p.
Open formula →Number Theory & SequencesModular Congruence
a ≡ b (mod n) ⇔ n | (a−b)
Defines equivalence modulo n.
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