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DigiCalcs

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Series sum calculators find the total of all terms in arithmetic, geometric, or special mathematical series. They have applications in finance (annuities), physics, and pure mathematics.

公式

Arithmetic: Sₙ = n(a₁+aₙ)/2; Geometric: Sₙ = a₁(1−rⁿ)/(1−r); General: Σₙ₌₁^N aₙ
a₁
first term
aₙ
last term
r
common ratio (geometric) — for geometric series
Sₙ
sum of first n terms

ステップバイステップガイド

  1. 1Arithmetic: Sₙ = n/2 × (2a + (n−1)d)
  2. 2Sum 1 to n: n(n+1)/2
  3. 3Sum of squares: n(n+1)(2n+1)/6
  4. 4Sum of cubes: [n(n+1)/2]²

解いた例

入力
1+2+3+...+100
結果
100×101/2 = 5050 (Gauss method)
入力
Arithmetic: a=1, d=2, n=10
結果
Sum = 10/2×(2+18) = 100

よくある質問

What is the difference between a sequence and a series?

Sequence: list of terms (1, 2, 3, ...). Series: sum of sequence terms (1+2+3+...).

How do I find the sum of integers from 1 to n?

Use the formula Sₙ = n(n+1)/2. For n=100: S = 100×101/2 = 5050.

What is sigma notation?

Σ notation compactly represents series sums: Σₙ₌₁^N aₙ means a₁ + a₂ + ... + aₙ.

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