1 5 Adding Subtracting Decimals WORD POWER Commutative

1. 5 Adding & Subtracting Decimals WORD POWER Commutative Associative Identity

1. 5 Adding and Subtracting Decimals q Commutative Property of Addition changing the _______does not affect the sum q 4+5=5+4 q Associative Property of Additionchanging the________ does not affect the sum q 4 + (6 + 5) = (4 + 6) + 5

1. 5 Adding and Subtracting Decimals q Identity Property of Addition – the sum of _____ and any number is that number. keyword: ______ q 4. 9 + 0 = 4. 9 q Inverse Property of Addition – the sum of a number and its inverse is equal to zero (0). keyword: ______ q 8. 6 + (-8. 6) = 0

Addition and Subtraction � Line Up the Decimals � “Drops Like a Rock”

� 3. 026 + 4. 7 + 1. 38 58 � 8. 9 + 0. 1 + 5. 0 � 5. 92 + 0. 4 + 3. 08 42 + 13. 9 + 74 + 19 + 1

Estimate and Find the Difference � According to the International Basketball Federation, the official distance around a basketball can be no more than 78. 0 cm. The distance can also be no less than 74. 9 cm. What is the difference between these distances? � 2. 7 – 0. 9 � 14. 5 � 0. 4 – 6. 97 – 0. 13

Subtracting Decimals from Whole Numbers � 50 – 7. 86 � 98 – 6. 8

Subtracting Decimals from Whole Numbers � 40 – 8. 32 � 82 – 4. 916

1. 6 Multiplying decimals v _____ – numbers to be multiplied v _____– the answer in multiplication v ________Property of Multiplication – changing the “order” of the factors does not affect the product. v 6 x 4=4 x 6

Multiplying Decimals �Put the longer number on top. �Ignore the decimals and multiply as usual. �“SWING IT”

�Find the product of the following: � 0. 47 x 8 � 6 x 0. 13 � 4. 37 x 5

q Decimals � 0. 3 x 0. 7 � 0. 3 (0. 2) �(0. 9) (0. l 4)

� A eucalyptus tree grows about 5. 45 m in one year. At that rate of growth, how much will the tree grow in 3. 5 years?

� One pound of tomatoes costs $1. 29. To the nearest cent, how much would 2. 75 pounds of tomatoes cost?

Using Properties � 4 x (8 x 0. 25) � 2 ( 5 x 2. 3 ) � 3. 1 x 1 x 100 � 500 x 0. 333 (2)

Homework: �Practice 1. 5 & 1. 6 �Be ready for a QUIZ on Friday.