1. Chapter 2
Lesson 3

2. Objective
Round decimal numbers
Use rounding to estimate an answer

3. Vocabulary
Rounding (approximation)
Estimate

4. Visual Rounding

5. Example 1 Round 16.0973 to the nearest ten b. tenth c. hundredth
a. 16 is closer to 20 than 10, so ≈ 20
…the 9 brings the 0 to a 1, so ≈ 16.1
the 9 is in the hundredth place followed by a 7, so is 16.10

6. Why Round?
Rounding is often used as a quick check on calculations. In general, we estimate by rounding to the highest place value of the smaller number for all operations. As a result, our estimated answer should be reasonably close to the exact answer.

7. Example 2 Find an estimated answer for each operation.
= = 440
2.849 – = 2.8 – 0.2 = 2.6
32.9 x 8.7 = 33 x 9 = 297
253 ÷ 12 = 250 ÷ 10 = 25

8. Guided Practice Round to the nearest ten. 27.8 13.2
Round to the nearest tenth.
3) 75.63
4) 4.45

9. Guided Practice
Round to the nearest hundredth. 5) ) Round to the nearest thousandth. 7) )

10. Homework
Pg. 49; 2-24 (even) Game Link