7th Grade Math

Not all numbers are rational numbers. The Greek letter π (pi)

represents the nonterminating and nonrepeating number whose first

few digits are 3.1415926.... This number is an irrational number.

Order Rational Numbers

List the numbers 3.44, π, 3.14, and 3.

−

4 in order from least to

greatest.

Line up the decimal points and compare using place value.

3.14 0 Annex a zero. 3.44 0 Annex a zero.

3.14 1 5926... π ≈ 3.1415926... 3. 444 ... 3. − 4 = 3.444...

Since 0 < 1, 3.14 < π. Since 0 < 4, 3.44 < 3. − 4.

So, the order of the numbers from least to greatest is

3.14, π, 3.44, and 3.

−

4.

Check Graph each number on a number line.

3.14 π 3.44 3.4

3.0 3.1 3.2 3.3 3.4 3.5 3.6

The number line confirms the order of the numbers is correct.

f. SCORES Class average scores on the last four science quizzes

were 0.82, _ 54 , 83%, and _^34. List the scores from least to greatest.

These common equivalents are used frequently. It will be useful to

memorize them.

Place Value Place Value Annexing a

zero to the right of the

decimal point does not

change the value of the

number.

Common Equivalents

41 = 0.25 = 25% ^15 = 0.2 = 20% 81 = 0.125 = 12.5% 101 = 0.1 = 10%

21 = 0.5 = 50% ^25 = 0.4 = 40% 83 = 0.375 = 37.5% 103 = 0.3 = 30%

^34 = 0.75 = 75% 53 = 0.6 = 60% ^13 = 0. 3 − = 33. − 3 % 107 = 0.7 = 70%

1 = 1.00 = 100% 54 = 0.8 = 80% 32 = 0. − 6 = 66. − 6 % _ 109 = 0.9 = 90%

Lesson 1C Rational Numbers 135

127_138_C3L1_895130.indd 135 12/31/09 12:35 PM