Percentage increase and decrease: Class 7 practice
Percentage change always compares the change with the ORIGINAL value: % change = (change ÷ original) × 100.. Read the method, follow the three worked examples, then try the six questions.
What you should know first
- Fractions to percentages
The idea behind percentage increase and decrease
Percentage change always compares the change with the ORIGINAL value: % change = (change ÷ original) × 100.
Step-by-step method
- Find the change (new − old).
- Divide by the original value.
- Multiply by 100 and say increase or decrease.
Worked example 1 (Basic)
A price changes from ₹420 to ₹441. Find the percentage increase.
- Change = 21
- (21 ÷ 420) × 100 = 5%
- Answer: 5% increase
Worked example 2 (Standard)
A price changes from ₹340 to ₹255. Find the percentage decrease.
- Change = 85
- (85 ÷ 340) × 100 = 25%
- Answer: 25% decrease
Worked example 3 (Challenge)
After a 25% increase, a school's enrolment is 250. What was it before?
- New = old × 1.25
- old = 250 ÷ 1.25 = 200
- Answer: 200
Common mistakes and misconceptions
- Dividing by the new value
- Treating a 20% rise then 20% fall as no change
Practice questions
- (Basic) A price changes from ₹340 to ₹442. Find the percentage increase.
- (Basic) A price changes from ₹520 to ₹676. Find the percentage increase.
- (Standard) A price changes from ₹600 to ₹300. Find the percentage decrease.
- (Standard) A price changes from ₹180 to ₹126. Find the percentage decrease.
- (Challenge) After a 50% increase, a school's enrolment is 570. What was it before?
- (Challenge) After a 50% increase, a school's enrolment is 600. What was it before?
Answer key with full working
- Q1: Change = 102 → (102 ÷ 340) × 100 = 30% → Answer: 30% increase
- Q2: Change = 156 → (156 ÷ 520) × 100 = 30% → Answer: 30% increase
- Q3: Change = 300 → (300 ÷ 600) × 100 = 50% → Answer: 50% decrease
- Q4: Change = 54 → (54 ÷ 180) × 100 = 30% → Answer: 30% decrease
- Q5: New = old × 1.5 → old = 570 ÷ 1.5 = 380 → Answer: 380
- Q6: New = old × 1.5 → old = 600 ÷ 1.5 = 400 → Answer: 400
Syllabus note
This skill is listed under "Comparing Quantities" for Class 7 in the NCERT/CBSE books. ICSE, IGCSE, IB and state boards may teach it in a different chapter or year.
Answers on this page are generated and automatically re-checked by a second, independent calculation. They have not been reviewed by a teacher — if you spot a problem, tell us on WhatsApp.
Related practice and notes
Frequently asked questions
Which chapter is percentage increase and decrease in?
"Comparing Quantities", Class 7 Maths (NCERT/CBSE). Other boards may place it differently.
How were the answers checked?
Answers on this page are generated and automatically re-checked by a second, independent calculation. They have not been reviewed by a teacher — if you spot a problem, tell us on WhatsApp.