As an Electrical Engineering graduation requirement, I had to take "engineering economy". I took full advantage of my 28S and completed most tests in half the time it took the others who were using tax tables. As I need room on my 28S, I'm entering these programs onto the mainframe and I thought I'd send it on ahead as long as it was typed in. The following 5 programs are subprograms... 1) FPIN: << -> i n '(1+i/100)^n' >> 2) FAIN: << -> i n '((1+i/100)^n-1)/(i/100)' >> 3) APIN: << -> i n 'i/100*(1+i/100)^n/((1+i/100)^n-1)' >> 4) AGIN: << -> i n '((1+i/100)^n-i/100*n-1)/(i/100*(1+i/100)^n-i/100)' >> 5) PGIN: << -> i n '((1+i/100)^n-i/100*n-1)/((i/100)^2*(1+i/100)^n)' >> The following 8 programs can be main programs or subprograms depending on the user's needs. Notation: P = present (or initial), F = final, G = gradient, A = payment F.P means find Final value given present value. arguments are present value, interest rate per term (e.g., 6) and number of terms. 1) F.P: << -> P i n 'P*FPIN(i,n)' >> 2) P.F: << -> F i n 'F/FPIN(i,n)' >> 3) F.A: << -> A i n 'A*FAIN(i,n)' >> 4) A.F: << -> F i n 'F/FAIN(i,n)' >> 5) A.P: << -> P i n 'P*APIN(i,n)' >> 6) P.A: << -> A i n 'A/APIN(i,n)' >> 7) A.G: << -> G i n 'G*AGIN(i,n)' >> 8) P.G: << -> G i n 'G*PGIN(i,n)' >> Examples: if you have $10,000 now and you want to know what it will be worth in 5 years at 6% interest per year... ! F ! 0 1 2 3 4 ! +--+--+--+--+--+ ----->time in years ! 5 ! P=$10,000 then F = F.P so you would enter: 10000 6 5 F.P which is $13,382.26 other graphical examples follow... ! ! F 0 1 2 3 n-2 ! F.P & P.F +--+--+--+ ... +--+--+ ! n-1 n ! P ! ! F.A & A.F ! F 0 1 2 3 n-2 n-1! +--+--+--+ ... +--+--+ ! ! ! ! ! A! A! A! A! A! P.A & A.P !A !A !A !A !A !A 0 ! ! ! ! ! ! +--+--+--+ ... +--+--+ ! 1 2 3 n-2 n-1 n ! P ! (n-1)G !nG 3G ! ! 2G ! ! ! A.G G ! ! ! ! 0 1 2! 3! 4! n-1! n! +--+--+--+--+ ... +--+ ! ! ! ! ! ! A! A! A! A! A! A! (n-1)G !nG P.G 3G ! ! 2G ! ! ! G ! ! ! ! 0 1 ! ! ! ! ! +--+--+--+--+ ... +--+ ! ! P !