Vili 
: ABBREVIATIONS AND NOTATION 
n = the probable life term in years of any article; or the term of amorti- 
zation. 
P = the present value of $1.00 due at the end of » years. 
P’ = the present value of an annuity of $1.00 receivable at the end of each 
year during » years. 
R = amount in the replacement fund expressed in percentage of the original 
investment. 
S = the sum of all annual replacement requirements estimated for a number 
of articles of various ages. 
Sn = the sum of all annual replacement requirements during » years.