AS/A2 Pure 1 Pure 3

P2 Topic 3: Sequences and series
n!
The function n! is read as "n factorial". 1! = 1 2! = 2.1 = 2 3! = 3.2.1 = 6 4! = 4.3.2.1 = 24 5! = 5.4.3.2.1 = 120 ... n! = n(n-1)(n-2)(n-3)...3.2.1 0! = 1. Find the value of n! for some other integer values of n. What is the largest value that you can get?

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Summary Factorials can produce very large numbers for relatively small values on n. For example 10! is over 3 million, whereas 20! is way over a million trillion. This page can work out that 170! = 7.257415615308004e+306, but cannot evaluate 171! at all. © MathsNet 2001