IMOClass 4 › Fractions

Fractions

Types of Fractions & Equivalent Fractions

A proper fraction has a numerator smaller than the denominator (¾). An improper fraction has a numerator equal to or larger than the denominator (5/4). A mixed fraction has a whole number and a fraction together (1¼).

Equivalent fractions show the same value, like ½ = 2/4 = 3/6. We get them by multiplying or dividing the numerator and denominator by the same number.

Example 1: Is 7/4 a proper or improper fraction?
Improper — the numerator 7 is bigger than the denominator 4.
Example 2: Write 5/4 as a mixed fraction.
5/4 = 1¼ (one whole and one-fourth).
Quick recap
  • Proper: numerator < denominator; improper: numerator ≥ denominator.
  • Mixed = whole number + fraction.
  • Equivalent fractions show the same value (½ = 2/4 = 3/6).
✓ Quick check
Which of these is a proper fraction?
In 3/4 the numerator is smaller than the denominator, so it is proper.
½ = ___/6. What is the missing numerator?
½ = 3/6, so the missing numerator is 3.

Comparing Fractions & Fraction of a Number

To compare fractions with unlike denominators, make the denominators the same and compare the numerators. To compare ⅔ and ¾, change both to twelfths: 8/12 and 9/12, so ¾ is bigger.

To find a fraction of a number, divide by the denominator and multiply by the numerator. ¾ of 12 = (12 ÷ 4) × 3 = 9.

Example 1: Which is bigger, ⅔ or ¾?
As 8/12 and 9/12, ¾ is bigger.
Example 2: Find ¾ of 12.
12 ÷ 4 = 3, and 3 × 3 = 9.
Quick recap
  • Make denominators equal, then compare numerators.
  • Fraction of a number: divide by the denominator, multiply by the numerator.
✓ Quick check
Which fraction is the largest?
⅔ is the largest of these fractions.
What is ⅓ of 18?
18 ÷ 3 = 6.

Adding & Subtracting Fractions

To add or subtract like fractions, keep the denominator and work with the numerators: ⅗ + ⅕ = ⅘.

For unlike fractions where one denominator is a multiple of the other, change them to the same denominator first. ½ + ¼ = 2/4 + ¼ = ¾, and ⅚ − ⅓ = 5/6 − 2/6 = ½.

Example 1: Add ½ + ¼.
½ = 2/4, so 2/4 + ¼ = ¾.
Example 2: Subtract ⅚ − ⅓.
⅓ = 2/6, so 5/6 − 2/6 = 3/6 = ½.
Quick recap
  • Like fractions: keep the denominator, add/subtract numerators.
  • Unlike fractions: make denominators the same first.
✓ Quick check
What is ⅖ + ⅗?
2/5 + 3/5 = 5/5 = 1 whole.
What is ¾ − ½?
½ = 2/4, so 3/4 − 2/4 = ¼.
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