Kerry>Okay, I'll show my ignorance. What is the difference between factor and divisor? The terms are commonly used interchangeably, even at MathWorld. <Kerry (c7) divisors(15) (d7) [1, 3, 5, 15] (c8) factor(15) (d8) 3 * 5 In[7]:= Divisors[15] Out[7]= {1, 3, 5, 15} In[8]:= FactorInteger[15] Out[8]= {{3, 1}, {5, 1}} Oops! Both Macsyma and Mathematica missed that factor of 1^69! Anyone using "factor" to mean other than prime factor or irreducible factor is *begging* to be misunderstood. Mathworld and Mathematica are both Wolfram products. Eric W, if he needs one, has no excuse. MikeG> I'm sorry to boggle about a non-essential part of this anecdote, but was the "million dollar question" really list the factors of 6? Or was that a small part of a larger, more interesting question? It is really hard to believe a question so simple (but apparently not so straightforward) was really the apex of a struggle for 1 million dollars... < The almost insuperable challenge was to perform mindreading on an inferior species, namely the pinhead producers. NeilB thinks the whole thing was scripted. --rwg