1. Principal: The money borrowed or lent out for a certain period is called the principal or the sum.
  2. Interest: Extra money paid for using other's money is called interest.
  3. Simple Interest (S.I.): If the interest on a sum borrowed for certain period is reckoned uniformly, then it is called simple interest. Let Principal = P, Rate = R% per annum (p.a.) and Time = T years. Then
    (i). Simple Intereest =P x R x T
    100
    (ii). P =100 x S.I.; R =100 x S.I.and T =100 x S.I..
    R x TP x TP x R