Fractions

Fractions as equal parts of a whole: equivalent fractions, simplest form, comparing, and adding and subtracting fractions and mixed numbers.

Key ideas

• In 3/4, the denominator 4 says how many equal parts the whole has; the numerator 3 says how many are taken.
• Equivalent fractions name the same amount: multiply or divide the top and bottom by the same number.
• A fraction is in its simplest form when the top and bottom have no common factor except 1.
• With the same denominator, the larger numerator is larger; with the same numerator, the smaller denominator is larger.
• To add or subtract, first write the fractions with a common denominator.
• For mixed numbers, add the wholes and the fractions separately, then simplify.

Remember

Watch out

• Adding tops and bottoms: 1/2 + 1/3 is not 2/5.
• Thinking 1/8 is bigger than 1/6 because 8 is bigger.
• Leaving an answer like 9/6 instead of 1 1/2.

Worked example