MATHEMATICS YEAR 4

FRACTIONS

NOTES(ADDING & SUBSTRACTING)

FRACTION: HOW TO ADD??

When the denominators are the same…

We have a rectangle that is cut into 4 pieces...

Each piece is and 2 pieces are

If we add , that would be…

14

24

4 41 2+

+ = = 34

When the denominators are different…

We need to find least common denominator (LCD)

For example,

The LCD for 2 and 3 is 6…

Change :

Change :

When the denominators are the same…

We have a rectangle that is cut into 6 pieces...

Each piece is . So,

HOW TO SUBTRACT??

16

56

- 26

56

= (5 pieces)

Take away 2 pieces,

So, 56

- 26

= 36

(3 pieces are left)

When the denominators are different…When the denominators are different…

FRACTIONSTASK : PROBLEM SOLVING (ADDING & SUBSTRACTING)

1. Sally ate ⅛ of cake and her sister ate ⅜ of it. What fraction did they eat altogether?

6. Arif mowed 3/10 of the lawn and Tina mowed 5/10 of the lawn. How much of the lawn has been mowed?

3. May planted 1/3 of her vegetable garden in the morning and another 1/3 of it in the afternoon. What fraction of her garden was planted in one day?

6. Jill studied math for 2 3/4 hours and Spanish for 1 2/3 hours. What was her total study time?

1. Ashley made a muffin. She used 1 2/3 cups of white flour and 3 cups of whole-wheat flour. How much flour did she use in all?

5. Sidhu had 8 dollars. He spent ⅝ of his money on candy and

another ¼ of his money on soda. What fraction of his money did he spend altogether?

1. Maria collects 1 ¼ boxes of litter from the roadside. Amy collects 2 ¾ boxes. How many boxes of litter did they collect in all?

5. There are seven pieces of pizza. Roy ate 3/8 of the pizza for dinner. He ate 3/8 of the pizza for a bedtime snack. How much of the pizza is left?

1. Miss Lee brought 4 4/5 pounds of candy to school. The students

in third grade ate 2 ½ pounds of the candy. How much did Miss Lee have left?

5. A plumber needs 8 ¾ metres of pipe to repair a water line. He has only 4 ½ metres of pipe. How many more metres of pipe does he need?

1. Adam bought 2 1/5 pounds ground beef. His mother used 1 3/5 pounds to make hamburgers. How much of the ground beef was left?

5. All of William's school books weigh a total of 5 1/2 kilograms. If he take away his math book, the total weight drops to 2 1/2 kilograms. How much does William's math book weigh?