Day Problems• Name the set(s) of numbers to which each number

belongs.

1. -12 2. 6

3. 4. 0

5. -4.8

5

12

Counterexample

• Counterexample – any example that proves a statement false

Using Counterexamples• Is each statement true or false? If it is false,

give a counterexample.

a. All whole numbers are rational numbers.

b. The square of a number is always greater than the number.

SOLUTIONS.

a. Every whole number can be written in the form n/1, so all whole numbers are rational. Statement is TRUE.

b. The square of 0.5 is 0.25, and 0.25 is not greater than 0.5. This statement is FALSE.

Comparing Numbers

• An inequality – a mathematical sentence that compares the value of two expressions using an inequality symbol, such as ≤ or ≥.

• < - less than, > - greater than

Ordering Fractions

• Write and in order from least to

greatest.

• Write each fraction as a decimal.

• From least to greatest, the fractions are

3,8

1,2

5

12

30.375

8

10.5

2

50.416

12

3

8

1,2

5,

12

Absolute value

• Absolute value of a number – the distance from 0 on a number line – ALWAYS positive.

Finding Absolute Value

• Find each absolute value.

1. | 12 | = 12

2.

3. | 0 | = 0

2

3 2

3

More Practice!!!!

• Class work – textbook p. 20 - 21 #1 – 41 odd

• Homework – STUDY