Best Percentage tricks and shortcuts

Learn the best math percentage tricks to solve percentage problems. All important Percentage formulas and shortcuts are explained along with the examples focusing on examinations like CAT, SSC, Bank PO, and Group D.

Percentage tricks

   

Percentage meaning: 

The percent is made of two words Per and cent, Per means "every" and cent means "hundred". It means how many of some things are there in 100.

For example, If a student gets 5 marks out of 10, he gets 50 percent of marks. This can be understood by a logic that if the same exam would have been of 100 marks then the student had gotten 50 marks that is why we are saying that he has got 50% of marks.

To convert in percentage, we multiply the fraction by 100.

For example, if the student has got 5 out of 10 marks, in fraction it can be written as 5/10

Now to convert fraction into percentage multiply fraction by 100, 
(5/10) * 100 = 50 %   

 Percentage shortcut tricks

• 1% of a number means 1/100 or 0.01 of that number
• 10% of a number means 10/100 or 0.1 of that number
• 50% of a number means 50/100 or just half of that number
• 100 % of a number means 100/100 of that number that is the number itself
• 200 % of a number means 200/100 of that number that is twice of the number
• 0.1   % of a number means 0.1/100 of that number, in decimal 0.001 of that number
• Now if we want to know the 5 % of a number simply calculate 10% and divide that by 2
• If we want to know 2% of a number just find 1% and twice it
• If we want to know 20% of a number find 10% and multiply it by 2
• Similarly, 30% of a number find 10% and multiply it by 3

Examples :

 Find 59 % of 45

59% of 45 = 50% of 45 + 10% of 45 -1% of 45

= 22.5 + 4.5 – 0.45 = 26.55

By doing the above method calculation becomes too easy and it can be easily calculated without pen and paper.

Find 27 % of 68

27 % of 68 = 10% of 68 + 10% of 68 + 5% of 68 + 1% of 68 + 1% of 68

= 6.8 + 6.8 + 3.4 + 0.68 + 0.68

= 13.6 + 3.4 + 1.36 = 18.36

Find 15.5 % of 1465

15.5 % of 1465 = 10 % of 1465 + 5% of 1465 + 0.5% of 1465

= 146.5 + 73.25 + 7.325 = 227.075

Important formulas to calculate the percentage

Formula 1: 

Percentage profit formula: 

% profit =	Profit * 100
	C.P.

=	(S.P - C.P.) * 100
	C.P.

Percentage loss formula: 

% Loss =	Loss * 100
	C.P.

=	(C.P - S.P.) * 100
	C.P.

Where, S.P. = Selling price
C.P. = Cost price

Formula 2: 

Percentage error formula:

% error =	| Exact value - Experimental value | * 100
	| Exact value |

Formula 3:

Percentage Reduction

The price of a commodity is increased by P%, than the percentage reduction in consumption, if the expenditure is the same as before

% Reduction in consumption =	P * 100
	100 + P

Percentage Increase

If the price of a commodity is decreased by P%, then the percentage increase in consumption, if the expenditure is the same as before

% Increase in consumption =	P * 100
	100 - P

Formula 4: If a number is successively increased by X % and then Y %, the effective percentage change is

[ ( X + Y + ( X * Y / 100 ) ] %

Formula 5: 40 % of ‘Y’ is 100, find Y

(40 / 100) * Y = 100

Y = 100 * (100 / 40) = 250

Formula 5: 

Population after "T" Years

Let the current population of a town is P now and it increases at an at the rate of R% than

Population after ‘T’ years 

P * [ 1 + ( R / 100)]T

The population before "T" years

P

[ 1 + ( R / 100)]T

Formula 6: 

Percentage Change 

Find the % change if a number ‘A is changed to ‘B’

[ Change in value of number / original number ] * 100 %

= [ ( B – A) / A ] * 100 %

Formula 7: 

If X is P% more than Y, then Y is less than X by

[P / (100 + P) * 100] %

Formula 8: 

If X is P% less than Y, then Y is more than X by

[P / (100 - P) * 100] %


Tag: percentage tricks, percentage short tricks



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