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Number - Connecting Fractions, Decimals, and Percentages

Grade 6IB

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

Equivalence across Forms: Fractions, decimals, and percentages are three ways to express parts of a whole. Imagine a '100-grid' square consisting of 100 small boxes; if 50 boxes are shaded, it represents the fraction 50100\frac{50}{100} (or 12\frac{1}{2}), the decimal 0.500.50, and the percentage 50%50\%.

Converting Fractions to Decimals: To convert a fraction to a decimal, divide the numerator by the denominator (numerator÷denominatornumerator \div denominator). On a vertical number line, the fraction 14\frac{1}{4} would be positioned at the same point as 0.250.25, exactly one-quarter of the way up from 00 toward 11.

Converting Decimals to Percentages: To turn a decimal into a percentage, multiply the value by 100100 and add the symbol %\%. Visually, this is equivalent to moving the decimal point two places to the right. For example, 0.850.85 becomes 85%85\%.

Converting Percentages to Fractions: A percentage is always a part 'out of 100'. To convert, place the percentage value over a denominator of 100100 and simplify. For instance, 60%=6010060\% = \frac{60}{100}, which simplifies to 35\frac{3}{5}. In a pie chart, this would look like a circle divided into 5 equal sectors with 3 sectors colored in.

Place Value Relationship: Decimals rely on place value where the first digit after the point is the 'tenths' (110\frac{1}{10}), the second is 'hundredths' (1100\frac{1}{100}), and the third is 'thousandths' (11000\frac{1}{1000}). 0.070.07 is specifically 77 hundredths, which is 7%7\%.

Comparing and Ordering: To compare fractions, decimals, and percentages, it is most efficient to convert all numbers into decimal form first. Once converted, you can stack them vertically by their decimal points to easily see which value is larger or smaller.

Terminating vs. Recurring Decimals: Some fractions like 15\frac{1}{5} result in a terminating decimal (0.20.2), while others like 23\frac{2}{3} result in a recurring decimal (0.666...0.666... or 0.6ˉ0.\bar{6}). A recurring decimal is indicated by a bar over the repeating digit or dots.

📐Formulae

Percentage=PartWhole×100\text{Percentage} = \frac{\text{Part}}{\text{Whole}} \times 100

Decimal=Numerator÷Denominator\text{Decimal} = \text{Numerator} \div \text{Denominator}

Percentage to Decimal=P÷100\text{Percentage to Decimal} = P \div 100

Decimal to Percentage=D×100\text{Decimal to Percentage} = D \times 100

Fraction to Percentage=(ab)×100%\text{Fraction to Percentage} = (\frac{a}{b}) \times 100\%

💡Examples

Problem 1:

Convert the fraction 35\frac{3}{5} into both a decimal and a percentage.

Solution:

Step 1: To find the decimal, divide 33 by 55. Since 3÷5=0.63 \div 5 = 0.6, the decimal is 0.60.6. \ Step 2: To find the percentage, multiply the decimal by 100100. 0.6×100=600.6 \times 100 = 60. \ Step 3: Add the percentage symbol: 60%60\%.

Explanation:

We use division to bridge the gap between fractions and decimals, and then use the base-100 property of percentages to complete the conversion.

Problem 2:

Express 0.450.45 as a fraction in its simplest form.

Solution:

Step 1: Identify the place value. 0.450.45 has two decimal places, so it is 4545 hundredths. \ Step 2: Write as a fraction: 45100\frac{45}{100}. \ Step 3: Simplify by finding the Greatest Common Divisor (GCD) of 4545 and 100100, which is 55. \ Step 4: 45÷5100÷5=920\frac{45 \div 5}{100 \div 5} = \frac{9}{20}.

Explanation:

Converting a decimal to a fraction involves using the place value as the denominator and then reducing the fraction by dividing both parts by their highest common factor.