Formulas To Solve Percentages Questions

Formulas for Percentages & Definitions

In mathematics, a percentage is a number or ratio expressed as a fraction whose denominator (bottom) is 100.
Thus, x percent means x hundredths, written as x%.
We express x% as a fraction as x/100

percentage formulas

Video on Percentages

Formulas and Explanation of Percentage are present in this Video

Percentages Formulas & Basic Concept

  • To calculate a % of b = (a * b)/100
  • To find what percentage of a is b = b/a × 100
  • To calculate percentage change in value
    Percentage change = [change/(initial value)] * 100
  • Percentage Increase/Decrease
    Percentage increase = (R/(100 + R) * 100)%
    Percentage decrease = (R/(100 – R) * 100)%
  • Successive Percentage Change
    If there are successive percentage increases of a % and b%, the effective percentage increase is: {(a + b + (ab/100)}%
  • Results on population
    Let the population of a town be P now and suppose it increases at the rate of R% per annum, then:
    1.Population after n years = P (1 +R/100)n
    2. Population n years ago = P/(1 +R/100)n
  • Results on Depreciation:
    Let the present value of a machine be P. Suppose it depreciates at the rate of R% per annum. Then:
    1.  Value of the machine after n years = P (1 – R/100)n
    2.  Value of the machine n years ago = P/ (1 – R/100)n
    3.  If A is R% more than B, then B is less than A by [R/(100 + R) * 100]%
    4.  If A is R% less than B, then B is more than A by [R/(100 – R) * 100]%

Please Login/Signup to comment