Tips for Solving Percentage Problems
Learn to handle percentages with these practical tips that will help you solve any exercise quickly and confidently.
Use the Base Formula
Remember that the percentage of a quantity is calculated as:
(percentage × quantity) / 100.
This is the foundation for all problems of this type.
Identify if it's an Increase or a Decrease (Discount)
If the value grows (interest, bonus, taxes), the percentage is added. If it decreases (sales, losses, discounts), the percentage is subtracted.
Convert Percentages to Decimals
It is sometimes easier to work with decimals: 25% = 0.25, 10% = 0.10, 8% = 0.08. Multiply the number by the decimal to get the result.
Check Your Calculations
Always verify your steps: First, calculate the percentage, then add or subtract depending on the type of problem. A small error can change the entire result.
Practice with Real-Life Situations
Apply percentages in your daily life: store discounts, taxes, tips, yields, etc. This will reinforce your understanding practically.
Use a Calculator if Needed
Don't hesitate to use a calculator to confirm your math. Accuracy is important, especially in financial or scientific contexts.
Easy Level Percentage Exercises
Learn to calculate percentages step by step with basic examples and real-world cases.
Exercise 1 — What is 25% of S/200?
We want to calculate how much 25% of a total value of S/200 represents.
| Total Value | S/200 |
|---|---|
| Percentage | 25% |
x = (25 × 200) / 100x = S/50
Exercise 2 — 30% Discount on S/150
We want to calculate the final price after applying a 30% discount.
| Original Price | S/150 |
|---|---|
| Discount | 30% |
x = (30 × 150) / 100 = S/45
150 − 45 = S/105
Exercise 3 — What percentage is 18 of 20?
Calculate the percentage that 18 represents out of a total of 20.
| Part | 18 |
|---|---|
| Total | 20 |
x = (18 × 100) / 20
x = 90%
Exercise 4 — 10% Salary Increase
A worker earns S/2,500 and receives a 10% increase. What will be their new salary?
| Current Salary | S/2,500 |
|---|---|
| Increase | 10% |
(10 × 2500) / 100 = S/250
2500 + 250 = S/2750
Exercise 5 — Body Fat Percentage
An athlete has 18 kg of body fat and weighs 80 kg. What percentage of their weight is fat?
| Total Weight | 80 kg |
|---|---|
| Body Fat | 18 kg |
(18 × 100) / 80 = 22.5%
Exercise 6 — 18% Tax on a Purchase (IGV)
A laptop costs S/3,000 and an 18% sales tax (IGV) is applied. What will be the final price?
| Base Price | S/3,000 |
|---|---|
| IGV (Sales Tax) | 18% |
(18 × 3000) / 100 = S/540
3000 + 540 = S/3,540
Exercise 7 — 12% Gas Price Increase
The price of gasoline was S/6.50 per liter. If it increases by 12%, what will be the new price?
| Initial Price | S/6.50 |
|---|---|
| Increase | 12% |
(12 × 6.50) / 100 = 0.78
6.50 + 0.78 = S/7.28
Exercise 8 — 15% Discount on Rent
An apartment costs S/1,800 per month, but a 15% promotional discount is applied. How much will be paid monthly?
| Original Price | S/1,800 |
|---|---|
| Discount | 15% |
(15 × 1800) / 100 = 270
1800 - 270 = S/1,530
Exercise 9 — 25% Monthly Salary Savings
If a person earns S/2,800 per month and decides to save 25% of their salary, how much money do they save and how much is left to spend?
| Monthly Salary | S/2,800 |
|---|---|
| Savings Percentage | 25% |
(25 × 2800) / 100 = 700
2800 - 700 = S/2,100
Exercise 10 — 30% Discount at a Clothing Store
A jacket costs S/250 and has a 30% discount. What is the final price?
| Original Price | S/250 |
|---|---|
| Discount | 30% |
(30 × 250) / 100 = 75
250 - 75 = S/175
Exercise 11 — 10% Interest on an Investment
You invest S/5,000 in a fund that generates a 10% annual interest. How much will you earn at the end of the year?
| Initial Capital | S/5,000 |
|---|---|
| Annual Interest | 10% |
(10 × 5000) / 100 = 500
5000 + 500 = S/5,500
Exercise 12 — 40% Discount on a Television
A television costs S/2,000 and is on sale with a 40% discount. How much do you pay?
| Original Price | S/2,000 |
|---|---|
| Discount | 40% |
(40 × 2000) / 100 = 800
2000 - 800 = S/1,200
Exercise 13 — 10% Tip at a Restaurant
The total restaurant bill is S/180. If you leave a 10% tip, how much do you leave and what is the total amount you pay?
| Consumption Total | S/180 |
|---|---|
| Tip | 10% |
(10 × 180) / 100 = 18
180 + 18 = S/198
Exercise 14 — Final Grade with Weighting
A student gets 80% on exams (60% of the total) and 90% on assignments (40% of the total). What is their final grade?
| Exams | 80% (60% weight) |
|---|---|
| Assignments | 90% (40% weight) |
(80 × 60) / 100 = 48
(90 × 40) / 100 = 36
48 + 36 = 84%
Exercise 15 — 25% Increase in Monthly Sales
A store sold S/40,000 in January. In February, its sales increased by 25%. How much did it sell in February?
| January Sales | S/40,000 |
|---|---|
| Increase | 25% |
(25 × 40000) / 100 = 10,000
40000 + 10000 = S/50,000
Exercise 16 — 20% Reduction in Electricity Consumption
A household used to pay S/180 monthly for electricity and reduces its consumption by 20%. How much will they pay now?
| Previous Consumption | S/180 |
|---|---|
| Reduction | 20% |
(20 × 180) / 100 = 36
180 - 36 = S/144
Exercise 17 — 20% Discount on Airplane Tickets
An airplane ticket costs S/1,200, but the airline offers a 20% discount for early purchase. How much will the passenger pay?
| Original Price | S/1,200 |
|---|---|
| Discount | 20% |
(20 × 1200) / 100 = 240
1200 - 240 = S/960
Exercise 18 — 15% Reduction in Body Weight
A person weighed 80 kg and managed to reduce their weight by 15% with diet and exercise. What is their new weight?
| Initial Weight | 80 kg |
|---|---|
| Reduction | 15% |
(15 × 80) / 100 = 12
80 - 12 = 68 kg
Exercise 19 — 10% Annual Depreciation on a Car
A new car costs S/60,000 and depreciates by 10% each year. What will its value be at the end of the first year?
| Initial Value | S/60,000 |
|---|---|
| Depreciation | 10% |
(10 × 60000) / 100 = 6,00060000 - 6000 = S/54,000
Exercise 20 — 12% Bonus on Salary
An employee earns S/3,500 monthly and receives a 12% bonus. How much will they collect in total that month?
| Base Salary | S/3,500 |
|---|---|
| Bonus | 12% |
(12 × 3500) / 100 = 420
3500 + 420 = S/3,920