1. Warm Up Problems Round each decimal to the nearest whole number.
1) 4.75
2) 34.1
3) 22.48

2. Estimate Products
Lesson 3-2

3. Objectives I can estimate the product of two decimal numbers.
I can explain my reasoning after solving a problem.

4. Rounding - Notes First underline the digit to be rounded.
Look at the digit to the right.
If the digit is 4 or less, keep the underlined digit the same.
If the digit is 5 or higher, add 1 to the underlined digit.
After rounding, all place values to the right of the underlined digit are zero.

5. Example 1 - Notes Estimate 8.7 x 2.8.
Round to the nearest whole number.
8.7 ~ 9
2.8 ~ 3
9 x 3 = 27
So the product is about 27.

6. Example 2 - Notes Estimate 42.6 x 37.2.
Round to the greatest place value to make it easier to compute mentally.
In this case the tens place.
42.6 ~ 40
37.2 ~ 40
40 x 40 = 1,600
So the product is about 1,600.

7. Example 1 and 2 – Guided Practice
Estimate each product.
1) 9.6 X 1.8
2) 68.4 x 21.3

8. Example 3 - Notes
A greyhound can travel 39.3 miles per hour. At this speed, about how far could a greyhound travel in 6.5 hours?
39.3 ~ 40
6.5 ~ 7
40 x 7 = 280.
So, about 280 miles.

9. Example 4 - Notes
Suppose one U.S. dollar is equal to 5.8 Egyptian pounds. About how many Egyptian pounds could you receive for $48.50?
5.8 ~ 6
48.5 ~ 50
50 x 6 = 300
So, it would be about 300 Egyptian pounds.

10. Example 3 and 4 – Guided Practice
3) Earth is rotating around the Sun about miles per second. About how many miles does it travel in 4.8 seconds?
4) A King Palm can grow about 2.1 feet per year. Estimate the height of the King Palm, in yards, after 15 years.

11. Example 5 - Notes
Patrice has $20 to buy binders. Binders cost $4.29 each. Does she have enough money? Explain your reasoning.
Estimate:
$4 x 5 = $20
$5 x 5 = $25
The actual price is somewhere in between $20 and $25, so she does not have enough money.