Article
Percentages are used in many everyday situations. You may encounter them when comparing prices, calculating discounts, reviewing statistics, or understanding financial information. For GED Math students, percentages are especially important because questions may present them in both direct calculations and real-world word problems. The good news is that percentage problems follow a few basic rules.
1. Understand what a percentage means
The word percent means per hundred. Therefore, 25% means 25 out of every 100. A percentage can be written as a fraction or decimal. For example: - 50% = 50/100 = 0.50 - 25% = 25/100 = 0.25 - 10% = 10/100 = 0.10 - 75% = 75/100 = 0.75 To convert a percentage into a decimal, divide it by 100. To convert a decimal into a percentage, multiply it by 100.
2. Find a percentage of a number
One of the most common percentage problems asks you to calculate a percentage of a given amount. Use this formula: Percentage amount = Percentage × Original number For example, calculate 20% of 150. First, convert 20% into a decimal: 20 ÷ 100 = 0.20 Then multiply: 0.20 × 150 = 30 Therefore, 20% of 150 is 30. This method works for percentages such as 8%, 15%, 35%, and 62%.
3. Calculate discounts
Discount questions are common in everyday financial situations. Imagine a jacket costs $80 and a store offers a 25% discount. First, calculate the discount: 0.25 × 80 = $20 Then subtract the discount from the original price: 80 − 20 = $60 The final price before any additional taxes or fees is $60. A common mistake is calculating the discount correctly but forgetting to subtract it from the original price.
4. Calculate percentage increases
Percentage increases describe how much a value has grown compared with its original amount. Suppose a monthly bill increases from $50 to $60. First, find the difference: 60 − 50 = 10 Next, divide the difference by the original amount: 10 ÷ 50 = 0.20 Finally, convert the decimal into a percentage: 0.20 × 100 = 20% The bill increased by 20%.
5. Calculate percentage decreases
Percentage decreases follow a similar process. Suppose a product's price falls from $120 to $90. First, calculate the decrease: 120 − 90 = 30 Then divide by the original price: 30 ÷ 120 = 0.25 Convert to a percentage: 0.25 × 100 = 25% The price decreased by 25%.
6. Avoid common percentage mistakes
Several errors can make percentage questions more difficult than they need to be. - Using the wrong original value: Percentage change is calculated using the original amount as the denominator. - Forgetting to convert: When using multiplication, convert the percentage to a decimal first. - Confusing the discount with the final price: A discount is the amount removed, not the amount paid. - Ignoring the question: Read carefully to determine whether you need the percentage, the original value, or the final amount.
7. Practice with real-world examples
Try creating percentage problems using shopping receipts, examination scores, or household expenses. This makes the calculations easier to understand because you can connect them to familiar situations. For example, if a student answers 36 questions correctly out of 40, the score percentage is: 36 ÷ 40 × 100 = 90%
Final tip
Practice converting percentages into decimals and solving word problems. Once you understand the basic formulas, many percentage questions become straightforward. Practice question: A pair of shoes costs $100. The store offers a 15% discount. What is the discounted price before tax? A. $15 B. $75 C. $85 D. $95 Answer: C. $85.
