Actuarial notation
Actuarial notation is a shorthand method to allow actuaries to record mathematical formulas that deal with interest rates and life tables. The core alphabet includes familiar letters such as i {\displaystyle i} for the effective rate of interest, v = ( 1 + i ) − 1 {\displaystyle v=(1+i)^{-1}} for the discount factor, δ {\displaystyle \delta } for the force of interest, l x {\displaystyle l_{x}} and q x {\displaystyle q_{x}} for life table entries, and function letters such as a , a ¨ {\displaystyle a,{\ddot {a}}} and A {\displaystyle A} for annuities and insurances.