Formula Review

Formula Review

6.1 Understanding Percent

part = percent x total

6.2 Discounts, Markups, and Sales Tax

discount=percent discount×original pricediscount=percent discount×original price

sale price=original price−discountsale price=original price-discount

sale price=original price−percent discount×original price=original price×(1−percent discount)sale price=original price-percent discount×original price=original price×(1-percent discount)

markup=percent markup×costmarkup=percent markup×cost

retail price=cost+markupretail price=cost+markup

retail price=cost+percent markup×cost=cost×(1+percent markup)retail price=cost+percent markup×cost=cost×(1+percent markup)

sales tax=purchase price×tax ratesales tax=purchase price×tax rate

Total price=purchase price+purchase price×tax rate=purchase price×(1+tax rate)Total price=purchase price+purchase price×tax rate=purchase price×(1+tax rate)

6.3 Simple Interest

I=P×r×tI=P×r×t

T=P+IT=P+I

T=P+P×r×tT=P+P×r×t

I=P×r365×tI=P×r365×t

FV=P+I=P+P×r×tFV=P+I=P+P×r×t

A=P×r×(1+r)t(1+r)t−1A=P×r×(1+r)t(1+r)t−1

PV=FV(1+rt)PV=FV(1+rt)

6.4 Compound Interest

A=P(1+rn)ntA=P(1+rn)nt

PV=A(1+rn)n×tPV=A(1+rn)n×t

Y=(1+rn)n−1Y=(1+rn)n-

16.6 Methods of Savings

A=P(1+rn)ntA=P(1+rn)nt

ROI=FV−PPROI=FV-PP

FV=pmt×(1+r/n)n×t−1r/nFV=pmt×(1+r/n)n×t-1r/n

pmt=FV×(r/n)(1+r/n)n×t−1pmt=FV×(r/n)(1+r/n)n×t-

16.7 Investments

annual return=(FVP)(1t)−1annual return=(FVP)(1t)-1

P/E=Share PriceDividendP/E=Share PriceDividend

Yld%=Annual DividendShare Price×100%Yld%=Annual DividendShare Price×100%

6.8 The Basics of Loans

I=P×rnI=P×rn

pmt=P×(r/n)×(1+r/n)n×t(1+r/n)n×t−1pmt=P×(r/n)×(1+r/n)n×t(1+r/n)n×t−

16.9 Understanding Student Loans

funding gap=total cost−all aidfunding gap=total cost−all aid

A=P(1+rn)ntA=P(1+rn)nt

pmt=P×(r/n)×(1+r/n)n×t(1+r/n)n×t−1pmt=P×(r/n)×(1+r/n)n×t(1+r/n)n×t−1

discretionary income=gross income−1.5×poverty guidelinediscretionary income=gross income−1.5×poverty guideline

6.10 Credit Cards

I=ADB×r×d365I=ADB×r×d365

6.11 Buying or Leasing a Car

pmt=P×(r/n)×(1+r/n)n×t(1+r/n)n×t−1pmt=P×(r/n)×(1+r/n)n×t(1+r/n)n×t−1

MD=P−RnMD=P−Rn

APR=2400×MFAPR=2400×MF

MF=APR/2,400MF=APR/2,400

PMT=(P−R)n+(P+R)×MFPMT=(P−R)n+(P+R)×MF

6.12 Renting and Homeownership

pmt=P×(r/12)×(1+r/12)12×t(1+r/12)12×t−1pmt=P×(r/12)×(1+r/12)12×t(1+r/12)12×t−1

T=pmt×12×tT=pmt×12×t

CoF=T−P