An arithmetic sequence goes from one term to the next by always adding (or subtracting) the same value(common difference). An example: 2, 4, 6, 8... 2 is added each time.  

Find the nth Arithmetic Sequence Term
an=a1+(n-1)d

The position of the term we are looking for is shown by n.
The first term (the starting number) in our sequence is shown by a.
The common difference (what we will add or subtract) is d.

56=51+(5-1)7 = 40
Example: Find the 6th term in an arithmetic sequence starting with 5 (the 1st term) and increasing by 7 each time: e.g. 5, 12, 19, 26, 33, 40

a = 1 + (n-1)



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©Jeff LeMieux, revised 2/2014