(x, x+n):	Age interval of interest where n is the length of the age interval
nmx:	Age-specific mortality rate for the age interval (x, x+n)
nqx:	Probability of dying in the age interval (x, x+n)
	nqx =1- exp(-n× nmx) where exp is base of natural log (2.71828...)
Ix:	Number of individuals surviving to the beginning of the age interval (x, x+n)
	Number of individuals alive at the beginning of age x
	Ix+n = Ix × (1-nqx)
ndx:	The number of individuals who die in the age interval (x, x+n)
	ndx = Ix × nqx
nLx:	Person-years of life in the age interval (x, x+n):
	The number of years of life lived by the cohort within the indicated age interval
	nLx = ndx ÷ nmx
Tx:	Total person-years of life contributed by the cohort after attaining age x
	Total number of age left to be lived by all individuals who survive to the beginning of age category x
	${\mathrm{T}}_{\mathrm{x}}={\sum }_x^{endoftable}nLx$
ex0:	Life expectancy (expected life at specified age x)
	Mean number of age remaining until death for individual surviving to the beginning of age category x
	ex0 = Tx ÷ Ix