Geometric progression calculator
Calculator for tasks related to geometric sequences such as sum of n first elements or calculation of selected n-th term of the progression.

Beta version

BETA TEST VERSION OF THIS ITEM
This online calculator is currently under heavy development. It may or it may NOT work correctly.
You CAN try to use it. You CAN even get the proper results.
However, please VERIFY all results on your own, as the level of completion of this item is NOT CONFIRMED.
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What do you want to calculate today?

 Choose a scenario that best fits your needs I know the first element of the sequence ($a_1$), common ratio of geometric sequence (q) and n and want to calculate the n-th element of the sequence ($a_n$)I know the first element of the sequence ($a_1$), common ratio of geometric sequence (q) and n and want to calculate the sum of first n elements of the sequence ($S_n$)I know the (n+1)-th element of the sequence ($a_{n+1}$) and the n-th element of the sequence ($a_n$) and want to calculate common ratio of geometric sequence (q)I know the (n+1)-th element of the sequence ($a_{n+1}$) and (n-1)-th element of the sequence ($a_{n-1}$) and want to calculate the n-th element of the sequence ($a_n$)

Calculations data - enter values, that you know here

 The n-th element of the sequence ($a_n$) => The sum of first n elements of the sequence ($S_n$) => Common ratio of geometric sequence (q)(ratio between succesive sequence elements: $a_{n+1} / a_n$) <= The first element of the sequence ($a_1$) <= N <= The (n+1)-th element of the sequence ($a_{n+1}$) => (n-1)-th element of the sequence ($a_{n-1}$) =>

Result: the n-th element of the sequence ($a_n$)

Summary
Used formulaShow source$a_n= a_1+{ q}^{ n-1}$
ResultShow source$2$
Numerical resultShow source$2$
Result step by step
 1 Show source$1+{1}^{1 - 1}$ Power of one number 2 Show source$1+1$ Simplify arithmetic 3 Show source$2$ Result
Numerical result step by step
 1 Show source$2$ Result

Some facts

• The geometric sequence is a sequence in which each successive element is r times greater than the previous one:
$a_{n+1} = a_n \cdot r$
where:
• $a_n$ - arbitrarily selected term,
• $a_{n+1}$ - the term just after $a_n$,
• $r$ - common ratio of geometric sequence.
• The above formula should be understood as follows: if I know some element of the geometric sequence ($a_n$) and its common ratio ($d$), then I can calculate the next one ($a_{n + 1}$).
• we can also define a geometric sequence in a slightly different way:
$a_{n} = a_{n-1} \cdot r$
where:
• $a_n$ - arbitrarily selected term (except the first one: $n \neq 1$),
• $a_{n-1}$ - the term just before $a_n$,
• $r$ - the common ratio of geometric sequence.
• Above alternative formula should be understood as follows: if I want to calculate some selected element of the geometric sequence ($a_{n}$), then I need to know the previous one ($a_{n-1})$) and the common ration ($r$).
• It is worth noting that the second formula does not work for the first element ($a_1$). This is because the first term as the only one does not have the previous element.
• In order to uniquely define the geometric sequence, it is enough to know two values:
• the first term $a_1$,
• and the ratio of two consecutive terms $r$, so called common ratio of geometric sequence:
$r = \dfrac{a_{n+1}}{a_n}$
• Geometric sequence is sometimes called a geometric progression.
• If you are interested in the properties of sequences, then you can check out our other calculators: