A fraction whose denominator is 100 is read as percent, for example 23/100 is read as twenty three percent or 23%. The symbol % is used for the term percent.
Percentage: Percent means per every hundred and denoted by the symbol %. A fraction with denominator 100 is called a Percent.
Percent as a fraction: Drop the % sign and multiply the given number by 1/100 and simplify it.
Percent as a decimal: Drop the % sign and insert or move the decimal point two places to the left.
Fraction as a percent: Multiply the fraction by 100, simplify it and mark % sign.
Decimal as a percent: Shift the decimal point two places to the right and mark % sign.
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
Loss % = (Loss x 100)/cp
Discounts
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
Interests
Principal (P): Money borrowed
Interest (I): Extra or additional money paid by the borrower.
Simple Interest (SI): Interest which is calculated uniformly on P throughout the loan period.
SI = (p x r x t)/100
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.
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.
$$ A = P \left (1 + \frac{R}{100} \right )^t $$