RRB JE 2019 Important Formulas and Shortcuts to Solve Percentage

Percentage is a very basic and important topic for Quantitative Aptitude as you can solve other topics speedily with its help. These formulas and shortcuts will be helpful for your upcoming Exams like Railway and SSC 2016. If you like it let us know. 

Percentage(%)

Percentage is per‑cent which means parts per hundred(1/100).

 If we have to convert the percentage into fraction then it is divided by 100.

Example 1:‑ If we write 45% then its equal to 45/100 or in fraction 9/20 or in decimal 0.45

If we have to convert fraction into percentage we have to multiple with 100.

Example 2:‑ if we write 3/5 in fraction it is equal to 60% =3/5x100=60.

Convert Percentage into Decimal:

• 20% = 20/100 = 0.5

Convert Decimal Into Percentage:

• 0.25 = (0.25 × 100) % = 25%
• 1.50 = (1.50 × 100) % = 150%

 Majorly used values shown in Percent, Decimal and Fraction

This table will help you solve questions very fast and easily.Try to remember these fractions because it will save lot of time in your examination.

Types of Formulas and Short Tricks 

Type 1: Percentage Increase/Decrease:
If the price of a commodity increases by R%, then the reduction in consumption so as not to increase the expenditure is: [R/ (100 + R)] x 100%
If the price of a commodity decreases by R%, then the increase in consumption so as not to decrease the expenditure is: [R/ (100 - R)] x 100%

Type 2: 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

 Type 3: 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)] x 100%

4. If A is R% less than B, then B is more than A by= [R/ (100 - R)] x 100%

Note: For two successive changes of x% and y%, net change = {x + y +xy/100}%

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