Simple-to-use number-pattern calculators for data sets such as arithmetic sequences and geometric sequences can be found on Calculator.net. In these calculators and similar tools, a missing value of a number sequence is calculated when a user specifies the defining pattern behind the set of numbers and selects the appropriate variables. AlteredQualia.com contains a number sequence solver that computes the defining pattern behind a valid set of numbers entered by a user.
The Fibonacci sequence number pattern calculator on Calculator.com is based on a pattern in which every number of a sequence is equal to the sum of the previous two numbers in the sequence. Users of the website enter a numerical value into the tool, and the corresponding Fibonacci sequence value is returned. Calculator.net's geometric sequence calculator works in a similar manner, but is based on a number pattern in which each number after the first is determined by multiplying the previous number by a nonzero constant. Users can calculate the value of a given position in a geometric sequence by entering the first number of the sequence and its common ratio.
Tools also exist to calculate the unknown number pattern of a given number set. WolframAlpha.com provides a tool that allows users to enter a set of numbers and determine the pattern of the sequence, if one exists.