Percentage and its Applications
Percent means per every hundred and denoted by the symbol %. A fraction with denominator 100 is called a Percent.

1. Profit and Loss
Cost Price (CP): Amount paid to buy an article.
Selling Price (SP): Amount at which an article is sold.
Profit or Gain: When SP > CP, the seller makes a profit or gain.
Gain = SP - CP
Loss: When CP > SP, the seller incurs a loss.
Loss = CP - SP
Gain and loss are always calculated on the CP.
Gain % = (Gain x 100)/CP
Relation between SP and CP: In case of Gain:
Marked price or list price (MP): Price at which a article is listed for sale.
Discount: Reduction in the marked price of an article.
Net selling price (SP): SP = MP - Discount
2. Interests
Principal (P): Money borrowed.
Interest (I): Extra or additional money paid by the borrower.
Amount (A): Total money paid by the borrower.
A = P + I or I = A – P
Rate (R): Interest on Rs. 100 for 1 year is known as the rate percent per annum.
Simple Interest (SI): Interest which is calculated uniformly on P throughout the loan period.
SI = (P x R x T)/100
Compound Interest (CI): Interest obtained during the first time period is added to the original P and amount becomes new P for the second time period and so on. The difference between the amount obtained at the last time period and original principal is called compound interest.