Percentage Tips And Tricks

Percentage Tips And Tricks

Basic fact and Formula
 

i. Now 1% we can express it as a 1%=1/100. Similarly we can write 10%=10/100 and 50%=50/100 ( 50 part of total 100 part ).

II. If a student get 40% marks in Math that means student got marks in math is 40 out of 100 of full marks.

III.
To Express p/q as a percentage:

We express it as p/q = (p/qx100)% .
so we can express like 1/4 = (1/4×100)% = 25% .
and Now, 0.4 = 4/10 = (4/10 x 100)% = 40% .

IV. If the price of a commodity increases by R%,then the reduction in consumption as not to increase the expenditure is [R/(100+R)x100]%

V. If the price of a commodity decreases by R%,then the increase in consumption as not to decrease the expenditure is [R/(100-R)x100]% 

VI. Results on Population :
Let the population of  a town be P now and suppose it increases at the rate of R% per annul, then :

1. Population after n years = P(1+R/100)n

2. Population n years ago = P/(1+R/100)n 
 

VII. Result on Depreciation :

Let the present value of a machine be P. Suppose it depreciates at the rate of R% per annul, 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 .
 

VIII.
If A is R% more then B, then B is less than A by
[R/(100+R)x100]% .

If A is R% less than B, then B is more than A by
[R/(100-R)x100]% .
Remember it :
It help in fast calculation in percentage:

1 = 100%    

1/2 = 50%

1/3 = 33×1/3%    

1/4 = 25%

1/5 = 20%    

1/6 = 16×2/3%

1/7 = 14×2/7%    

1/8 = 12×1/2%

1/9 = 11×1/9%    

1/10 = 10%

1/11 = 9×1/11%    

1/12 = 8×1/3%

1/13 = 7×9/13%

 

Percentage Type 1 Shortcut Tricks

Example 1:
If the difference between 45% of a number and 3/5th of that number is 18. What is the number?

Solution:
Let the number be a .
Then a x 45% – a x 3/5 = 18
a x 45% – a x 60% = 18 ∴( 60% = 3/5 )
a x 15% =18
a = 100×18 = 1800/15 = 120

Tricks:
we know 3/5 = 30%
45% – 30% = 15 %
15% = 18 = 120

Percentage Type 2 Shortcut Tricks

Example 1:
Bibhas work in shop and his 30% of income is  Rs.1800 . Now Find the 65% of his income and also find the 1 / 5 of Bibhas income .

Solution: 30% = 1800 So, 65% = 1800 x 65 / 30 = 3900
Shortcut Trick: 1800 x 65 / 30 = 3900.
Solution: we know that 1 / 5 = 20% so, 1800 x 20 / 30 = 1200.

Percentage Type 3 Shortcut Tricks

Example 1:
Bijoy spend his money from his saving in different way that is he spends 30% on travel,10% on food,15% on wages and 22% on purchase a bike and after that all expenditure he saved 4600.Find the how much he spent on bike.
 

Answer :
Let the total income of bijoy x. then total expenditure from income  X x (30%+10%+15%+22%)=X x 77% =Total savings= X x 23%
X = 4600 x 100 / 23 = 20000 and expenditure on Bike = 22% so,20000 x 22 / 100 = 4400.

Shortcut Tricks
The total income as 100% so ,(100% – 30%+10%+15%+22%) = 77% and now (100% – 77% ) = 23%
Bike Expenditure is now 4600 x 22 / 23 = 4400

Percentage Shortcut Tricks 4

Example 1 :
Sanjay got 88 marks in Hindi , 81 marks in Science , 74 marks in Maths , 68 marks in Social Science and 57 marks in History . The maximum marks of each subject is 100 . How much overall percentage of marks did he get ?
 

Answer :
Percentage = 368 x 100 / 500 = 73.6

 

Percentage calculation on population Shortcut Tricks

Example 1:
If a town the present population is 52500 and it is decreased by 20% per annul .What will be its population 2 years hence.

Solution:
We know
Population after n year = P(1+R/100)n
So Here we
P = 52500
R=20% ( decreased )
n = 2 years.
Population after 2 years

Short Tricks :
= 52500 x 80/100 x 80/100
= 33600