Let Principal = P, Rate= R% per annum, Time = n years.

When interest is compounded Annually :
Amount = P
(1 +
^{R}/_{100})^{n}

When interest is compounded Half-yearly :
Amount = P
(1 +
^{ R/2 }/_{100})^{2n}

When interest is compounded Quarterly :
Amount = P
(1 +
^{ R/4 }/_{100})^{4n}

When interest is compounded Annually but time is in fraction, say 3 ^{2}/_{5} :
Amount = P
(1 +
^{R}/_{100})^{3} X
(1 +
^{ (2/5 R)}/_{100})

When Rates are different for different years, say R1%, R2%, R3% for
lst, 2nd and 3rd year respectively.
Then, Amount = P
(1 +
^{R1}/_{100})(1 +
^{R2}/_{100})(1 +
^{R3}/_{100})

Present worth of Rs.x due n years hence is given by : _{Present Worth = }^{ x } ^{(1 +
R/100
)n}