Adding, Subtracting, Multiplying, and Dividing Decimals! And a few fractions

Multiplication

100

.21 x 11

2.31

200

After multiplying the two decimals how do you decide how many decimal places the answer will have?

Count up the number of decimal places in the problem.

300

.2 x 3

.6

400

.02 x 11

.22

500

There are 15 people in a room. Each person ate 2/3 of a pizza. There was no pizza remaining. How many pizzas were in the room?

10

Division

100

What number goes under the division bar? 7.13 ÷ 1.2

7.13

200

2.4 ÷ .2

12

300

6.48 ÷ .4

16.2

400

24.3 ÷ .03

810

500

An MP3 can hold 350 songs of music. Each song is about about 2.5 minutes in length. About many how many songs can the MP3 player store?

140

Addition

100

When you add decimals you should first line up the __________ ___________. 

Decimal Points

200

2.23 + 4.1

6.33

300

1.33 + .2

What is -3.67

400

2.11 + 5.2

7.31

500

A triangle has sides of length 14.463 cm, 11.34 cm, and 20.875 cm. What is the perimeter of the triangle? 

47.678 cm

Subtraction

100

When you subtract decimals you should first line up the ________ _______? 

decimal points

200

2.44 - 1.1

1.34

300

34.67 - 2.1

32.57

400

5.33 - .2

5.13

500

22.567 - 1.22

21.347

Fractions

100

Convert 2 1/2 to an improper fraction

5/2

200

1/6 × 2/3

1/9

300

4 × 8/15

2 2/15

400

4 1/3 ÷ 6 1/2

What is 2/3

500

4 1/2 ÷ 3/4

6