Give formulae for half yearly calculation of compound intrest formula.

The formula for compound interest, compounded once per year, is:

A = P (1+r) ^t, where r is the annual interest rate as a decimal fraction and t is the number of years.

If interest is compounded twice per year, then the above formula is changed to:

A = P (1+r/2) ^ (2t), where the '2' indicates twice-per-year compounding.

If interest is compounded n times per year, then the above formula is changed to:

A = P (1+r/n) ^ (nt).