Compound Interest important notes - Aptitude Questions and Answers

Let Principal = P, Rate = R% per annum, Time = n years.
When interest is compound Annually:
Amount = P 1 + R n
100
When interest is compounded Half-yearly:
Amount = P 1 + (R/2) 2n
100
When interest is compounded Quarterly:
Amount = P 1 + (R/4) 4n
100
When interest is compounded Annually but time is in fraction, say 3 years.
Amount = P 1 + R 3 x 1 + R
100 100
When Rates are different for different years, say R₁%, R₂%, R₃% for 1^st, 2^nd and 3^rd year respectively.
Then, Amount = P 1 + R₁ 1 + R₂ 1 + R₃ .
100 100 100
Present worth of Rs. x due n years hence is given by:
Present Worth = x .
1 + R
100

Amount = P		1 +	R		n
			100

Amount = P		1 +	(R/2)		2n
			100

Amount = P		1 +	(R/4)		4n
			100

Amount = P		1 +	R		3	x		1 +	R
			100						100