WELCOME!
We will explore lots of exciting topics in math and examine applications of the concepts learned in real world settings. So, let’s begin with the basics, and then see how we apply them to actual math problems that are encountered in every day math.
WHOLE NUMBER ADDITION
PROPERTIES, ESTIMATION, AND PROBLEM SOLVING
We begin by looking at addition properties. The addition properties help organize multi-step math problems. By following the properties, problems may be reordered and regrouped to solve mentally.
Sometimes a quick estimate of an amount is all that is needed. We’ll look at a problem where all that is needed is a close number rather than the actual number.
Basic computations begin with adding whole numbers. Lining up place value is crucial to adding whole numbers correctly. Estimate first to find an approximate answer and then add to find the actual answer.
To solve a word problem read it through carefully. It helps to read it through more than once. Look for key words that are clues for solving the problem.
Mental Addition Using Properties  Use the commutative, associative, and identity properties to simplify.
Look for sums that add up to multiples of ten.
Steps Reasons 31 + 0 + (66 + 9) Identity Property 31 + 0 = 31 31 + (66 + 9) Commutative Property 66 + 9 = 9 + 66 31 + (9 + 66) Associative Property (31 + 9) + 66 Add 31 + 9 first 40 + 66 Add on 66 106 |
Estimation
As the principal looks over the numbers he decides to round them to the nearest 100 to get a quick estimate. He looks at the hundreds place, then the number to the right (tens place). He remembers that if the number is 5 or higher, round up.
The principal estimates there are approximately 900 students in his school. (100 + 200 + 200 + 200 + 100 + 100) |
Whole Number Addition
Estimate the sum, and then solve: 245 + 378 + 2995
Estimation: 300 + 400 + 3000 = 3700 The estimated answer is 3700.
Solution: Line up the numbers from right to left so that all place values are in line. Answer: 245 + 378 + 2995 = 3618
Check: The estimated answer, 3700, is close to 3618. |
Problem Solving - Addition
Read through this problem and solve. Look for key words that aid in determining the correct method for solving.
The 4-H club mowed lawns to earn money for a trip to the baseball park. On Monday they earned $150, on Tuesday they earned $126, and on Wednesday they earned $100. What is the total earnings?
The key word is total – this is an addition problem because all of the money is being put together.
150 + 126 + 100 = $376 |
 |
 Click on the icon to find and practice topics for this unit. |
| Unit 1 Estimating Sums to the Nearest Hundreds Worksheet |
| Click here to watch the video on the associative property. |
| Unit 1 Define Activity |
| Click here to watch the video on the commutative property. |
| Unit 1 Define Activity |
| Click here to watch the video on the distributive property. |
| Unit 1 Define Activity |
