Also, please read the answerline carefullyit makes some very fine distinctions] Stirling's approximation for factorial has a "n over this number, all to the n" term. The pdf of the standard normal distribution involves this number to the negative one-half x squared. The integral from 1 to this number of the function "1 over x" is equal to 1. This number equals the sum, over all the natural numbers n, of 1 over n-factorial. (*) It's also the limit, as n goes to infinity, of the quantity "1 plus 
Also, please read the answerline carefullyit makes some very fine distinctions] Stirling's approximation for factorial has a "n over this number, all to the n" term. The pdf of the standard normal distribution involves this number to the negative one-half x squared. The integral from 1 to this number of the function "1 over x" is equal to 1. This number equals the sum, over all the natural numbers n, of 1 over n-factorial. (*) It's also the limit, as n goes to infinity, of the quantity "1 plus 1-over-n" to the n, which you might run into while calculating compound interest. The derivative of "this number to the x", is just "this number to the x." This transcendental irrational is the base of the natural logarithm. For 10 points, name this number approximately equal to 2.718.
Also, please read the answerline carefullyit makes some very fine distinctions]
e [or Euler's number; or Napier's constant; do NOT accept or prompt on any answer with the words "constant" or "Mascheroni," since "Euler's constant" is a different number]