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'How Does Your Function Grow?' printed from

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Four enthusiastic mathematicians are asked to think of a function involving the number 100. The challenge is to think of the function which is biggest for big values of n
  • Archimedes chooses a logarithm function $$A(n) = \log(100n)$$
  • Bernoulli decides to take 100th powers $$B(n) = n^{100}$$
  • Copernicus takes powers of 100 $$C(n) = 100^n$$
  • and, finally, de Moivre, who likes to be different, chooses the factorial function which he claims will be quite big enough without any reference to 100 at all $$D(n) = n\times (n-1)\times (n-2)\times \dots \times 2\times 1$$

    Which function is biggest for large values of n? Can you determine a value beyond which you know this function will be biggest?

    [Extension: To find the exact switch-over value will be difficult and will require the clever use of a spreadsheet or computer.]

    What could you say if the 100s were replaced by a million? billions? Create a convincing argument to prove your results to the mathematicians.