The above is the part of Quantitative Aptitude, it is just a topic name "Percentages". From this you can easily learn few basics of how numericals of mathematics that to be dealt with few shortcuts. I hope this will be useful for everyone to understand few things about Quantitative Aptitude. Specially this is for the persons who are preparing for the competative exams.

1. Quantitative Aptitude
Topic: Percentages - 1
Msp Classes

2. Percent
Per (/) ; Cent (100)
Simply Percent means /100

3. Basic
Percentage
Values

4. 10%
• 10/100
• 1/10
20%
• 2/10
• 1/5
30%
• 30/100
• 3/10
40%
• 4/10
• 2/5
50%
• 5/10
• 1/2

5. 60%
• 6/10
• 3/5
70%
• 70/100
• 7/10
80%
• 8/10
• 4/5
90%
• 90/100
• 9/10
100%
• 100/100
• 1 = Total

6. Additional Values that everyone have to know for easy calculations:
= 3/5
12%
24% =6/25
=9/25
36%
44% =11/25
=
3/20
15%
76%
=
19/25
=
21/2
5
84%
.125
%
=1/8

7. 100 comes in 2 table, 4 table, 5 table, 10 table, 20 table,
25 table & 100 table.
Take the maximum common cut values from
2,4,5,10,25,50
For Example:
1. 80% = 80/100
= 4/5

8. 1. 20% of 100
= 20/100 * 1000
= 200
2. 40% of 2500
=> 10% * 4
=> 250 * 4 = 1000
3. 24% of 2500 + 42% of 10,000 + 12.5% of 1600 + 0.125 *
888
= (6/25 * 2500) + (42/100 * 10,000) + (1/8 * 1600) +
(1/8 * 888)
= 600 + 4200 + 200 + 111
= 5111

9. Percentage based concepts:
Population
Salary
Marks
Numbers
Venn Diagram
Election

10. Main Formulas:
1. Percentage Increase = (Difference/ Lowest Number) * 100
2. Percentage Decrease = (Difference/ Highest Number) * 100
3. “x” is what percentage of “y” :
= (x/y) *100
4. Percentage Change = x + y + (x*y/100)
5. Net Percentage Change:
= (Difference/More value) * 100
(or)
= (Difference/Less value) * 100

11. 1. Population in 2016 is 10,000. It increases 10% in 2017 and
again 10% in 2018. What is the percentage & population in
2018 ?
2016 – 10,000 ; 2017 – 10% ↑ ; 2018 – 10% ↑
Formula: x + y + (xy/100)
X = 10 Y = 10
Total increase in percentage = {10+10+ (100/100)} = 20 + 1 =
21%
Already the Total Population in 2016 is 10,000 then 21%
increased in 2018. So, the new populatin in 2018 become 121%
as that of 2016.
121% of 10,000 = 121/100 * 10,000 = 12100

12. Chain Rule:
Forward chain rule:
10,000 * 110/100 * 110/100 = 12100
2016 2017 2018
Reverse Chain Rule:
X * 110/100 * 110/100 = 12100
2016 2017 2018
X = 10,000

13. If A is 80% of B and B is 20% of C, then What
percent of A is C ?
A = 80% of B = (4/5)*B
B = 20% Of C = (1/5)*C
A : B : C
A:B:C = 4:5:25 4 : 5 : (5)
(1) : 1 : 5
= 4 : 5 : 25
25/4 * 100 = 625
Answer = 625

14. A student multiplied a number by 3/5 instead of
5/3. what is the percentage error in the calculation
?
Given values: 3/5, 5/3
We have only two numbers 3 & 5. So find the
number which is commonly divided by 3 & 5.
The following number is 15. Multiply 15 using
both 3/5 & 5/3
15 * 3/5 = 9; 15 * 5/3 = 25
Their Difference = 25 – 9 = 16
Net Percentage = 16/ 25 * 100
Answer = 64

15. If the numerator of a fraction is increased by 15%
and its denominator increases by 8%, the value of
fraction is 15/16. Find the original Fraction Value.
Solution,
x * (100+15) 15
--------------- = ----
y * (100-8) 16
x 15 92 3
--- = --- x ---- = ---
y 16 115 4

16. Raju purchased a Maruti Car 3 years ago for
Rs.2 lakhs. It’s value preciated each year at
the rate of 25% per annum. What is the
present value ?
a) Rs. 3,34,000 b) Rs. 84,375 c) Rs.
87,435
Solution;
= 2,00,000 * 75/100 * 75/100 *
75/100
= 75 * 75 * 75 * 200000/1000000
= 84,375
Answer : Rs. 84,375

17. The price of sugar is reduced by 20%, now a
person can buy 500g more sugar for Rs.36.
The original price of the sugar per kilogram
was ?
Solution;
20% of 36 = 7.2 i.e the price of 500g
Then price for 1kg = Rs. 14.4 i.e reduced
price
The original price = 14.4 + 3.6 = Rs. 18