Class Notes: Subtracting a Fraction from a Whole Number

Objective

Learn how to subtract a fraction from a whole number.

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Steps to Subtract a Fraction from a Whole Number

1. Convert the Whole Number to a Fraction

   • Place the whole number over 1.
     • Example: 7 becomes 7/1

2. Get a Common Denominator

   • Multiply both the numerator and denominator of the whole number's fraction by the denominator of the second fraction.

3. Rewrite Both Fractions with the Common Denominator

   • Example:
     • If the second fraction is 2/3, multiply 7/1 by 3/3 to get 21/3.

4. Subtract the Numerators

   • Keep the denominator the same.
   • Subtract: New Numerator = (Numerator of whole number's converted fraction) - (Numerator of second fraction)
   • Write the result as an improper fraction.

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Examples

Example 1: (7 - \frac{2}{3})

1. Convert 7 to a fraction:
   • (7 = \frac{7}{1})
2. Get a common denominator (3):
   • (\frac{7}{1} \times \frac{3}{3} = \frac{21}{3})
3. Now subtract:
   • (\frac{21}{3} - \frac{2}{3} = \frac{19}{3})

Answer: (\frac{19}{3})

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Example 2: (3 - \frac{4}{5})

1. Convert 3 to a fraction:
   • (3 = \frac{3}{1})
2. Get a common denominator (5):
   • (\frac{3}{1} \times \frac{5}{5} = \frac{15}{5})
3. Now subtract:
   • (\frac{15}{5} - \frac{4}{5} = \frac{11}{5})

Answer: (\frac{11}{5})

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Summary

• Always convert the whole number to a fraction.
• Find a common denominator to match the fractions.
• Subtract the numerators while keeping the denominator the same.
• Write your answer as an improper fraction if necessary.