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, lx denotes the expected number of lives attaining age x. l0 is set to 100,000. The progression of mortality is as follows:-
l20 = 98,496 - (i.e. of the population of 100,000 achieving birthhood, a fortunate 98,496 individuals will reach the age of 20)
l30 = 97,645
l40 = 96,500
l50 = 93,925
l60 = 86,714
l70 = 68,055
l80 = 36,128
l90 = 7,857
l100 = 271