Arithmetic Sequence Calculator
Find the nth term and sum of a constant-difference sequence.
Tool inputs stay in your browser · optional AI search sends your query
Good to know: aₙ = a₁+(n−1)d. Sum = n(a₁+aₙ)/2. n is a positive integer. First term and common difference may be negative or fractional; the difference is constant between adjacent terms.
How to use it (step by step)
- 1Fill in the boxes: “First term”, “Common difference”, “Number of terms”. Example numbers are already there so you can see how it works; replace them with yours.
- 2The result updates instantly as you type (on a phone it is below the boxes).
- 3The bold line is the main answer. Tap Copy next to any value to copy it.
Words to know
- Logarithm / root
- A root undoes a power (the square root of 9 is 3). A logarithm asks “what power gives this number?” (log₁₀ 100 = 2).
- Sequence
- A list of numbers that follows a rule. Arithmetic adds the same amount each time (2, 4, 6); geometric multiplies (2, 4, 8).
- Fraction / ratio
- A fraction is a part of a whole (3/4 = three of four parts). A ratio compares two amounts (2:1 = twice as much).
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