Example 1
The price of an article is first increased by 10% and then decreased by 30%. What is the net percentage change in its price?
Answer: B) 23% decrease
Net change = 10 − 30 − (10 × 30)/100 = -23%, i.e. a 23% decrease.
Percentage questions for competitive exams: rules, worked examples and practice
Percentage means "per hundred". Percentage questions ask for a part of a number, a percentage change, or the net effect of successive changes.
Key rules and formulas
- x% of N = N × x ÷ 100.
- Percentage change = (new − old) ÷ old × 100.
- Successive changes of a% and b% give a net change of a + b + ab/100 % (use negative values for decreases).
- Useful fractions: 25% = 1/4, 12.5% = 1/8, 20% = 1/5, 33⅓% = 1/3.
Common traps
- Taking the percentage of the new value instead of the old one.
- Assuming a rise and an equal fall cancel out (they give a net loss).
Where Percentage is asked
- IBPS Clerk Prelims (Numerical Ability)
- IBPS PO Prelims (Quantitative Aptitude)
- RRB Group D (Mathematics)
- RRB NTPC CBT 1 (Mathematics)
- SBI Clerk Prelims (Numerical Ability)
- SBI PO Prelims (Quantitative Aptitude)
- SSC CGL Tier 1 (Quantitative Aptitude)
- SSC CGL Tier 2 (Mathematical Abilities)
- SSC CHSL Tier 1 (Quantitative Aptitude)
Worked examples
Example 2
What is 5% of 1,880?
Answer: A) 94
5% of 1,880 = 5 × 1,880 / 100 = 94.
Example 3
The price of an article is first increased by 10% and then decreased by 20%. What is the net percentage change in its price?
Answer: C) 12% decrease
Net change = 10 − 20 − (10 × 20)/100 = -12%, i.e. a 12% decrease.
More Percentage practice questions
- The price of an article is first increased by 25% and then decreased by 25%. What is the net percentage change in its price?
- What is 20% of 1,040?
- What is 5% of 1,080?
Frequently asked questions
What is Percentage in competitive exams?
Percentage means "per hundred". Percentage questions ask for a part of a number, a percentage change, or the net effect of successive changes.
Which exams ask Percentage questions?
On MockBazaar, Percentage questions appear in IBPS Clerk Prelims, IBPS PO Prelims, RRB Group D, RRB NTPC CBT 1, SBI Clerk Prelims, SBI PO Prelims, SSC CGL Tier 1, SSC CGL Tier 2, SSC CHSL Tier 1.
What is the most common mistake in Percentage?
Taking the percentage of the new value instead of the old one.