Mathematics
Grade 7
15 min
Percent of a number
Percent of a number
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1
Introduction & Learning Objectives
Learning Objectives
Convert percentages to equivalent decimals.
Convert percentages to equivalent fractions.
Calculate the percent of a whole number using decimal multiplication.
Calculate the percent of a decimal number using decimal multiplication.
Solve real-world problems involving finding the percent of a number.
Estimate the percent of a number.
Ever wonder how stores calculate discounts on your favorite items? 🛍️ Or how much tax you pay on a new gadget?
In this lesson, you'll learn how to find a specific percentage of any number. This skill is super useful for understanding sales, taxes, tips, and even statistics, helping you make sense of the numbers all around you.
Real-World Applications
Calculating sales tax on a purchase.
Determining discounts during...
2
Key Concepts & Vocabulary
TermDefinitionExample
PercentA ratio that compares a number to 100, meaning 'per hundred'. It represents a part of a whole.25% means 25 out of 100.
DecimalA number that uses a decimal point to represent parts of a whole, often used as an equivalent form of a percentage for calculations.0.25 is the decimal equivalent of 25%.
FractionA way to represent a part of a whole, written as a numerator over a denominator. Percentages can be converted to fractions.1/4 is the fraction equivalent of 25%.
OfIn mathematics, the word 'of' often indicates multiplication, especially when finding a percent of a number.25% of 80 means 25% multiplied by 80.
WholeThe total amount or the entire quantity from which a part is taken.In '25% of 80', 80 is the whole number.
PartThe porti...
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Core Formulas
Converting Percent to Decimal
P\% = P \div 100
To use a percentage in calculations, you must first convert it to a decimal by dividing the percentage number by 100 (or moving the decimal point two places to the left).
Converting Percent to Fraction
P\% = \frac{P}{100}
Another way to represent a percentage is as a fraction with a denominator of 100. This fraction should then be simplified to its lowest terms.
Calculating Percent of a Number
\text{Part} = \text{Percent (as decimal or fraction)} \times \text{Whole}
To find a percentage of a number, convert the percentage to its decimal or fractional form and then multiply it by the whole number.
5 more steps in this tutorial
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Challenging
A student tried to find 20% of $65.50. Their calculation was 20 × 65.50 = 1310. What was their fundamental error?
A.They used the wrong operation; they should have divided.
B.They multiplied by 20 instead of the decimal equivalent, 0.20.
C.They placed the decimal incorrectly in the final answer.
D.They should have converted $65.50 to a whole number first.
Challenging
A video game costs $59.90. It is on sale for 25% off. A sales tax of 8% is calculated on the discounted price. What is the total amount paid?
A.$48.52
B.$44.93
C.$49.88
D.$48.22
Challenging
If 20% of a number is 50, what is 70% of that same number?
A.175
B.250
C.350
D.140
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