Simple & Compound Interest – Quantitative Aptitude Notes

Simple & Compound Interest

Important Terms

Principal: The amount of money borrowed or lent for a certain period.

Interest: Extra amount of money paid while returning the principal amount to the lender.

Simple Interest: In Simple Interest, the interest is applied to the principal amount alone.

Compound Interest: In Compound Interest, interest is applied on the principal plus interest earned quarterly, half-annually or annually.

Simple Interest Formulae

Simple Interest = (P x R x T) / 100

P: Principal amount

R: Interest Rate% per Annum (yearly)

T: Time in years

Compound Interest Formulae

Compound Interest is similar to Simple Interest. The difference is that in Compound Interest, the Interest is added to principal amount after every term (quarterly, half-annually or annually).

Compound Interest, if compounded annually: 

Compound Interest = P (1  + R/100 )n

Compound Interest, if compounded half-annually: 

Compound Interest = P (1  + R/100 )2n

Compound Interest, if compounded quarterly:

Compound Interest = P (1  + R/100 )4n