7th Grade: Operations with Rational Numbers

Adding Rational Numbers

100

3.15 + 2.25

5.40

200

0.38 + (-1.2)

-0.82

300

9/25 + (-17/25)

-8/25

400

-5/4 + 1 1/12

-1/6

500

To make a small amount of play dough, you can mix 1 cup of flour, 1/2 cup of salt and 1/2 cup of water. What is the total amount of ingredients added to make the play dough?

2 cups

Subtracting Rational Numbers

100

8/11 - 3/11

5/11

200

- 1 1/3 - 5/4

-2 7/12

300

-0.06 - (-0.86)

0.8

400

-5/12 - (-2/24)

-1/3

500

The snowfall in Rochester, NY in the winter of 1999-2000 was 91.5 inches. Normal snowfall is about 76 inches per winter. How much more snow fell in the winter of 1999-2000 than is normal?

15.5 inches

Multiplying Rational Numbers

100

5(1/3)

1 and 2/3

200

-3.2 x 5

-16

300

-1/6 (-2/3)

1/9

400

-2.57 (-.5)

1.285

500

Joe had a breakfast party. He invited four of his best friends. Each friend brought 3.4 cups of coffee. How much coffee did they all bring together?

13.6 cups

Dividing Rational Numbers

100

1/4 divided by 3/8

2/3

200

-20 divided by 0.5

-40

300

-15 divided by -5/8

24

400

Emma bought 2 and 1/2 yards of ribbon to make bows for 4 of her friends. How much yard will she use for each ribbon?

5/8 yards

500

How do you determine if your answer is positive or negative when:

Adding/Subtracting
Multiplying/Dividing

Add/Subtract: Same signs -> keep sign

                    Different signs -> choose the bigger #

Mult/Divide: Molly Dolly