The idea in brief. Divide both fraction numbers by the same whole number until the fraction cannot be reduced further. Divide the numerator and denominator by the same whole number until they cannot both be divided exactly again. In the lesson. In the last lesson, you found that nine twelfths is equal to three quarters. We divided the numerator and the denominator by 3. Today, we will write a fraction in its simplest form. Divide the numerator and the denominator by the same number. Stop when only 1 divides both.
Lesson video, with the working
Simplest form
5 min 23 s
The film teaches 3 questions in turn. Each question shows first; its working is written as the film explains it.
Mei cuts a banana cake into 12 equal slices. She gives away 8 slices. What fraction of the banana cake does she give away? Give your answer in its simplest form.
fraction given away = 8/12
8/12 = (8 ÷ 2)/(12 ÷ 2) = 4/6
4/6 = (4 ÷ 2)/(6 ÷ 2) = 2/3
Ans: 2/3
Example 1 of 2
A chocolate bar has 10 equal squares. Kavin eats 6 squares. What fraction of the chocolate bar does he eat? Give your answer in its simplest form.
fraction eaten = 6/10
6/10 = (6 ÷ 2)/(10 ÷ 2) = 3/5
Ans: 3/5
Example 2 of 2
A paper strip has 18 equal parts. Lin colours 6 parts. What fraction of the strip does she colour? Give your answer in its simplest form.
fraction coloured = 6/18
6/18 = (6 ÷ 2)/(18 ÷ 2) = 3/9
3/9 = (3 ÷ 3)/(9 ÷ 3) = 1/3
Ans: 1/3
How to solve it
Write the fraction from the question. 8 slices out of 12 is eight twelfths.
Ask whether the numerator and the denominator can both be divided exactly by the same number. 8 and 12 can both be divided by 2.
Divide both by that number: 8 divided by 2 is 4, and 12 divided by 2 is 6.
Ask again. 4 and 6 can be divided by 2 again, which gives 2 and 3.
Stop when only 1 divides both. Two thirds is in its simplest form.
Divide the numerator and the denominator by the same number. Stop when only 1 divides both.
Practice questions with worked solutions
Question 1 is free to try. The other 6 open in the free trial, each with its solution film.
How do you answer simplest form fractions questions in P3?
This page teaches your child to write a fraction in its simplest form, following the P3 outcome on expressing a fraction in its simplest form.
What your child learns here
This page teaches your child to write a fraction in its simplest form, following the P3 outcome on expressing a fraction in its simplest form. It builds on equivalent fractions and returns whenever a later answer has to be simplified.
Know that a fraction is in simplest form when 1 is the only whole number that divides both the numerator and the denominator.
Divide both numbers by the same whole number, in one step or in several smaller steps.
After each step, check whether the two numbers can still both be divided.
Find the fraction from a picture or a story first, including the part not shaded or not used, and then simplify it.
Does the answer make sense?
A fraction in simplest form names the same amount as the one it came from, with a smaller top and bottom number, or the same ones if it was already simplest. Your child can test the answer by looking for any whole number other than 1 that divides both its numbers.
How to practise these questions
The Basic question practises dividing the numerator and denominator by the same number. The Intermediate questions add fractions that need more than one division, or a larger common factor, and one that is already in simplest form. The Challenge questions ask your child to simplify a fraction read from a picture, such as the unshaded part of a grid or two kinds of shading combined. When simplifying is stuck, play that question's solution film and return to it later from Revision. Its multiple-choice Basic questions give 3/12, 6/10 or 10/12 and ask for the equal fraction among four, so your child divides both numbers by a common factor; the working is written out and there is no film.
Questions parents ask
Is simplest form taught in Primary 3? Yes. Expressing a fraction in its simplest form is one of the Primary 3 Fractions outcomes in the MOE syllabus, listed under Equivalent fractions. It is also the last step when adding and subtracting related fractions later in this chapter.
Does my child have to simplify a fraction in one step? No. Dividing by 2 and then by 2 again reaches the same answer as dividing by 4 at once. Smaller steps are fine, as long as your child keeps going until 1 is the only number that divides both.
How does my child know which number to divide by? Start with 2 if both numbers are even, then try 3 and 5. Times tables help here, since the real question is whether both numbers appear in the same table.
