Donna Kirk

Formula Review

6.1 Understanding Percent

part = percent x total

6.2 Discounts, Markups, and Sales Tax

$discount = percent discount \times original price$

$sale price = original price - discount$

$sale price = original price - percent discount \times original price = original price \times (1 - percent discount)$

$markup = percent markup \times cost$

$retail price = cost + markup$

$retail price = cost + percent markup \times cost = cost \times (1 + percent markup)$

$sales tax = purchase price \times tax rate$

$Total price = purchase price + purchase price \times tax rate = purchase price \times (1 + tax rate)$

6.3 Simple Interest

$I = P \times r \times t$

$T = P + I$

$T = P + P \times r \times t$

$I = P \times \frac{r}{365} \times t$

$F V = P + I = P + P \times r \times t$

$A = P \times \frac{r \times {(1 + r)}^{t}}{{(1 + r)}^{t} - 1}$

$P V = \frac{F V}{(1 + r t)}$

6.4 Compound Interest

$A = P {(1 + \frac{r}{n})}^{n t}$

$P V = \frac{A}{{(1 + \frac{r}{n})}^{n \times t}}$

$Y = {(1 + \frac{r}{n})}^{n} - 1$

6.6 Methods of Savings

$A = P {(1 + \frac{r}{n})}^{n t}$

$ROI = \frac{F V - P}{P}$

$F V = p m t \times \frac{{(1 + r / n)}^{n \times t} - 1}{r / n}$

$p m t = \frac{F V \times (r / n)}{{(1 + r / n)}^{n \times t} - 1}$

6.7 Investments

$annual return = {(\frac{F V}{P})}^{(\frac{1}{t})} - 1$

$P / E = \frac{Share Price}{Dividend}$

$Yld % = \frac{Annual Dividend}{Share Price} \times 100 %$

6.8 The Basics of Loans

$I = P \times \frac{r}{n}$

$p m t = \frac{P \times (r / n) \times {(1 + r / n)}^{n \times t}}{{(1 + r / n)}^{n \times t} - 1}$

6.9 Understanding Student Loans

$funding gap = total cost - all aid$

$A = P {(1 + \frac{r}{n})}^{n t}$

$p m t = \frac{P \times (r / n) \times {(1 + r / n)}^{n \times t}}{{(1 + r / n)}^{n \times t} - 1}$

$discretionary income = gross income - 1.5 \times poverty guideline$

6.10 Credit Cards

$I = \frac{ADB \times r \times d}{365}$

6.11 Buying or Leasing a Car

$p m t = \frac{P \times (r / n) \times {(1 + r / n)}^{n \times t}}{{(1 + r / n)}^{n \times t} - 1}$

$MD = \frac{P - R}{n}$

$APR = 2400 \times MF$

$MF = APR / 2,400$

$P M T = \frac{(P - R)}{n} + (P + R) \times MF$

6.12 Renting and Homeownership

$p m t = \frac{P \times (r / 12) \times {(1 + r / 12)}^{12 \times t}}{{(1 + r / 12)}^{12 \times t} - 1}$

$T = p m t \times 12 \times t$

$CoF = T - P$