Assume that you are interested in understanding how much must be saved regularly over a period of time in order that at the ending of the period you have a particular amount. To answer such question here we manipulate the equation as

FVA_n  = A[((1 + k)ⁿ - 1)/k]

That demonstrates the relationship in between FVA_n , A, K and

A = [k/((1 + k)ⁿ - 1)]FVA_n    ............................Eq(11)

Equation 11 assists in answering this question. The periodic deposit is easily A and is acquired by dividing FVA_n by FVIFA_k,n. In Eq 11[k/((1 + k)ⁿ - 1)]  is the inverse of FVIFA_k,n and is termed as the sinking fund factor.