how do we calculate no. of stereoisomers in a compound?

Dear Satyan,

                 For calculation of stereoisomer you have to see 2 important things in the compound i.e. 1)chiral centre.

if in a compound there is 2 chiral centre only then no of stereoisomer will be 2ⁿ i.e. 2²=4 but you have to be aware that if in a molecule if there is any pos or cos(i.e. plane of symmetry or centre of symmetry)  exist then total no of stereoisomer will be 2²-1=3.

2) no of double bond which is responcible for geometrical isomer but be sure that the two valencies of same carbon must be different.

    And if in a compound both chiral centre and double bond present then add them and get no of isomer according to the above example.