In the whacky world of

actuarial tables l

_{x} is defined as the number of lives still alive in a given population, where x indicates the age.

For example, in the population mortality table **ELT15 (Males)** based on the mortality of the population of England and Wales during the years 1990, 1991 and 1992, l_{x} denotes the expected number of lives attaining age x. l_{0} is set to 100,000. The progression of mortality is as follows:-

l_{20} = 98,496 - (i.e. of the population of 100,000 achieving birthhood, a fortunate 98,496 individuals will reach the age of 20)

l_{30} = 97,645

l_{40} = 96,500

l_{50} = 93,925

l_{60} = 86,714

l_{70} = 68,055

l_{80} = 36,128

l_{90} = 7,857

l_{100} = 271