Tips And Tricks And Shortcuts For Simple Interest Problems

Simple Interest Shortcut formulas.

• If the interest on a sum of money is \frac{1}{x}of the principal, and the number of years is equal to the rate of interest then rate can be calculated using the formula: \mathbf{\sqrt{\frac{100}{x}}}

• The rate of interest for t₁ years is r₁%,  t₂ years is r₁%,  t₃ years is r₃ %.  If a man gets interest of Rs x for (t₁+ t₂ + t₃ = n)  years, then principal is given by:
  \mathbf{\frac{x*100}{r_{1}t_{1}}} + r₂t_{2 +} r₃t₃

• If sum of money becomes x times in t years at simple interest, then the rate is calculated as R = \mathbf{\frac{100(x-1)}{t}} %

• If a sum of money becomes x times in t years at simple rate of interest, then the time is calculated as t = \mathbf{\frac{100(x-1)}{R}}

• If an amount P₁ is lent out at simple interest of R₁% p.a. and another amount of P₂ at simple interest of R₂% p.a, then the rate of interest of the whole sum is given by: R = \mathbf{\frac{P_{1}R_{1}+P_{2}R_{2}}{P_{1}+P_{2}}}