Fractions with the Same Denominator
Primary 4 · Mathematics
Fractions with the Same Denominator
Lesson 2 of 5
30 min
Let's begin
Mugisha and Umutoni each get a mandazi of the same size. Mugisha cuts his into 2 equal pieces and eats 1. Umutoni cuts hers into 4 equal pieces and eats 2. "I ate more pieces!" says Umutoni. But did she really eat more?
Look at the fraction bars. The shaded parts all stop at the same place:
So 12 = 24 = 48. Fractions that are the same size are called equivalent fractions. Umutoni ate 24, which is the same as Mugisha's 12. Nobody ate more!
To make an equivalent fraction, multiply (or divide) the numerator and the denominator by the same number: 13 = 26, because 1 × 2 = 2 and 3 × 2 = 6.
A fraction is in its simplest form when no number except 1 divides both the numerator and the denominator. To simplify, divide both by a common factor. Use the greatest common factor (GCF) to finish in one step.
When the denominators are the same, the pieces are the same size. So the fraction with more pieces (the bigger numerator) is the bigger fraction.
38 < 58, because 3 pieces are fewer than 5 pieces of the same size.
Explore: the Fractions: Equality simulation lets you build a fraction and then find other fractions that are equal to it.
Tip
Same size pieces? Count them! If the bottom numbers are the same, just compare the top numbers. And whatever you do to the top of a fraction, do the same to the bottom.
Work each one in your exercise book first. Then tap Show answer to check.
How many sixths are equal to 13?
Answer: 2 sixths: 13 = 26. The denominator was multiplied by 2, so multiply the numerator by 2 too.
Simplify 410.
Answer: 25 (divide both by 2)
Simplify 912.
Answer: 34 (divide both by 3)
Write <, > or = : 79 ___ 49
Answer: >. The pieces are the same size, and 7 pieces are more than 4.
Put in ascending order: 512, 112, 1112, 712
Answer: 112, 512, 712, 1112
What you learned today
Sources and credits
The stories, Rwandan worked examples, diagrams and practice questions were written by Ganzaa.
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