Principal-Interest-Time Formulas

Simple Interest → A = Prt
Compound Interest → A = P(1 + r)t
Continuous Interest → A = Pert

Annuities

An annuity is a stream of level payments over the course of a specified time.

Present Value of an Annuity Immediate (Payments at the end of a period:

an|i  =  Payment * (1 - vn)
  i

v  =  1
  1 + i

Present Value of an Annuity Due (Payments at the beginning of a period:

än|d  =  Payment * (1 - vn)
  d

d  =  i
  1 + i

Accumulated Value of an Annuity Immediate (Payments at the end of a period:

sn|i  =  Payment * ((1 + i)n - 1)
  i

Accumulated Value of an Annuity Due (Payments at the beginning of a period:

sn|d  =  Payment * ((1 + i)n - 1)
  d

Perpetuity

An perpetuity is an infinite stream of level payments
Present Value of a Perpetuity Immediate  =  Payment
  i

Present Value of a Perpetuity Due  =  Payment
  d

Depreciation Summary
MethodDepreciation DtBook Value Bt
Straight Line
A - S
N

(1-Time/N) * Asset Value + Salvage Value * Time / N
Sum of the Years Digits
(A - S) * (N - t + 1)
Σ 1st n integers

Bt
  
= S +
  
Σ first (n - t) integers * (A - S)
Σ first n integers

Declining Balanced * A * (1-d)(t-1) where d = 1 - (A/S)1/nA x (1 - d)t
Sinking Fund
(A - S) x (1 + j)(t - 1)
sn|j

Bt
  
= A -
  
(A - S) x st|j
sn|j

Weighted Average Cost of Capital (WACC) and Capital Asset Pricing Model (CAPM)
re = rf + Β(rm - rf)
WACC = rD * (1 - T)*(Debt%)+ rE*(Equity Percentage)