Important Percentage Formulas 

A Percentage is
a number or ratio expressed as a fraction of 100. Percent
is denoted by the symbol %.  

For example, x
percent is denoted by x%

x% = x/100, 

e.g.: 25%=25/100=1/4

1) To express x/y as
a percent, we have x/y=(x/y×100)%

Example:
1/4=(1/4×100)%=25%

2) If the price of a
commodity increases by R%, the reduction in consumption so as not to increase
the expenditure = [R/(100+R)×100]%

3) If the price of a
commodity decreases by R%, the increase in consumption so as not to decrease
the expenditure = [R/(100−R)×100]%

4) If the population
of a town = P and it increases at the rate of R% per annum, then Population
after n years = P(1+R/100)^{^n}

5) If the population
of a town = P and it increases at the rate of R% per annum, then Population
before n years = P/(1+R/100)^n

6) If the present
value of a machine = P and it depreciates at the rate of R% per annum, Then
Value of the machine after n years = P(1−R/100)^{^n}

7) If the present
value of a machine = P and it depreciates at the rate of R% per annum, Then
Value of the machine before n years = P/(1−R/100)^{^n}

Percentage Notes:Also Read: