In a magazine recently there was a discussion about probability.
The author asserted that the probability of the event in question was approximately
(1 - 10-21)1025
How small is this number?
(1-10^-21)^(10^25)=
((1-10^-21)^(10^21))^(10^4)
The first part is very close to 1/e, so the answer is (1/e)^10000, or approximately 1x10^-4343.