PROBLEM SOLVING PLAN 1.READ and UNDERSTAND the problem. 2.PLAN how to solve the problem. 3.SOLVE it. 4.LOOK BACK and CHECK to see if your answer makes sense. Do You Remember?

Adding and Subtracting Decimals Lesson 1-5

The Basic Steps: 1. Line up the numbers by the decimal point. 2. Fill in missing places with zeroes. 3. Add or subtract.

Addition Properties Commutative Property of Addition: Numbers can be added in any order. Example: 5+3=3+5 Associative Property of Addition: Numbers can be grouped in any way. Example: (7+3) + 5 = 7 + (3+5) Identity Property of Addition: The sum of any number and zero is that number. Example: = 18

Mental Math Addition properties can be used to quickly find sums. Example: What is ? We can use an addition property to quickly add this. First, change the order: ________________ property. Then, group the first two addends together: ( ) ________________ property = commutative associative

Example: This can estimate to , which is 43. (Compatible numbers) The answer is close to the estimate.

Subtracting The addition properties do not work for subtraction. Estimate and subtract to find what the answer is close to. Subtract to find the real answer.

Subtracting Across Zeroes If you have several zeroes in a row, and you need to borrow, go to the first digit that is not zero, and borrow. All middle zeroes become 9’s. The final zero becomes 10.

Example: 15 –

Play Hotel Decimalfonia to help you add and subtract decimalsHotel Decimalfonia Practice Adding Decimals and Subtracting Decimals from AAA MathAdding Decimals Subtracting Decimals Complete Adding/Subtracting Decimals worksheet

Homework Time pg , #2-40 evens, pg. 32, #2-14 evens The above image is of Detroit, MI from