Simple percentage calculation examples

📚 Quick Study Guide

• 🔢 What is Percentage? Percentage means 'out of 100'. The symbol % represents percentage.
• ➗ Formula for Percentage: To find what percentage a number $x$ is of another number $y$, use the formula: $\frac{x}{y} \times 100$.
• 🛍️ Calculating Percentage of a Number: To find $p$% of a number $y$, use the formula: $\frac{p}{100} \times y$.
• 💰 Percentage Increase: To calculate the percentage increase from an old value $O$ to a new value $N$, use the formula: $\frac{N - O}{O} \times 100$.
• 📉 Percentage Decrease: To calculate the percentage decrease from an old value $O$ to a new value $N$, use the formula: $\frac{O - N}{O} \times 100$.
• 💡 Tips for Success: Always read the problem carefully to identify what values are given and what you are asked to find. Double-check your calculations!

✍️ Practice Quiz

1. What is 20% of 50?
   1. 5
   2. 10
   3. 15
   4. 20
2. If a shirt originally costs $25 and is on sale for 20% off, what is the discount amount?
   1. $2
   2. $3
   3. $4
   4. $5
3. What percentage of 80 is 20?
   1. 15%
   2. 20%
   3. 25%
   4. 30%
4. A student scored 80 out of 100 on a test. What is their percentage score?
   1. 60%
   2. 70%
   3. 80%
   4. 90%
5. If a price increases from $10 to $12, what is the percentage increase?
   1. 10%
   2. 15%
   3. 20%
   4. 25%
6. What is 150% of 30?
   1. 35
   2. 40
   3. 45
   4. 50
7. If 30% of a number is 60, what is the number?
   1. 100
   2. 150
   3. 200
   4. 250