Formulas for Compound Interest Problems

Important Compound Interest formulas

• Formulas for Compound Interest (When Interest is Compound Annually)
  • Amount = P\mathbf{(1+ \frac{r}{100})^{T}}
  • Compound Interest =Total amount – Principal
  • Rate of interest (R) = [\mathbf{(\frac{A}{P})^{\frac{1}{T}}}− 1]%

• Formulas of Compound Interest (When Interest is Compound Half Yearly)

• • Amount = P (1+ \mathbf{\frac{{\frac{r}{2}}}{100})^{2T}}
  • Compound Interest = Total amount – Principal

• Compound Interest Formulas (When Interest is Compound Quarterly)
  • Amount = P (1+ \mathbf{\frac{{\frac{r}{4}}}{100})^{4T}}
  • Compound Interest = Total amount – Principal

• Formulas of Compound Interest (When Interest is Compound Monthly)
  • Amount = P (1+ \mathbf{\frac{{\frac{r}{12}}}{100})^{12T}}

• Compound Interest Formulas (When Interest is Compounded Annually but time is in fraction, say 2(\mathbf{\frac{3}{2}})years )
  • Amount = P (1+ \mathbf{\frac{r}{100}})^{2}(1+ \mathbf{\frac{\frac{3}{2}r}{100}})

• Formulas of Compound Interest (When rates are different for different years)
  • Amount = P (1+\frac{r_{1}}{100}) (1+\frac{r_{2}}{100}) (1+\frac{r_{3}}{100})

• Formulas for Compound Interest (Present worth of Rs. x due n years)
  • Present worth =    \frac{x}{(1+\frac{r}{100})}