1. Rounding Objective: Round two-digit numbers to the nearest ten. Round three-digit numbers to the nearest hundred. Round using decimals Estimate sums and differences. Estimate products and quotients.

2. Vocabulary Rounding Approximately Nearest Hundreds Tenths Thousandths Place value Differences Almost Close to Estimation About how many Tens Thousands Hundredths Sums Reasonable Nearly

3. The rounding poem Find your number Look right next door 4 or less, just ignore 5 or more add one more!

4. Rounding two-digit numbers Redondeando números de dos digitos 26 1.Underline the number in the place value you will round. 2. Look at the number to the right of the underlined number. Two-digit number will be rounded to the nearest ten. 3.If the number to the right is 0, 1, 2, 3, or 4, then the underlined number stays the same. 4.If the number to the right is 5, 6, 7, 8, or 9, then the underlined number needs to go up one more number. RULES FOR ROUNDING 5.Every number to the right of the underlined number becomes a zero. 30 So we can say that the number 26 is closer to 30 than to 20.

5. Rounding three-digit numbers Redondeando números de tres digitos 520 1.Underline the number in the place value you will round. 2. Look at the number to the right of the underlined number. Three-digit number will be rounded to the nearest hundred. 3.If the number to the right is 0, 1, 2, 3, or 4, then the underlined number stays the same. 4.If the number to the right is 5, 6, 7, 8, or 9, then the underlined number needs to go up one more number. RULES FOR ROUNDING 5.Every number to the right of the underlined number becomes a zero. 50 So we can say that the number 520 is closer to 500 than to 600. 0

6. 202630 26 is closer to 30 than to 20. 520600500 520 is closer to 500 than to 600.

7. Estimating sums 12 + 8 ------- 12 + 8 ------- First, round all the numbers using the RULES FOR ROUNDING Then, perform the operations. 10 + 10 ------- 10 + 10 ------- 20 20

8. Estimating differences 25 - 11 ------- 25 - 11 ------- First, round all the numbers using the RULES FOR ROUNDING Then, perform the operations. 30 - 10 ------- 30 - 10 ------- 20 20

9. RULES FOR ROUNDING 1.Underline the number in the place value you will round. 2. Look at the number to the right of the underlined number. 3.If the number to the right is 0, 1, 2, 3, or 4, then the underlined number stays the same. 4.If the number to the right is 5, 6, 7, 8, or 9, then the underlined number needs to go up one more number. 5.Every number to the right of the underlined number becomes a zero.

10. The rounding poem Find your number Look right next door 4 or less, just ignore 5 or more add one more!

11. Now you practice. Round these numbers. 25 78 36 158 689 324 30 80 40 200 700 300

12. Practice rounding sums and differences 128 + 42 ------- 128 + 42 ------- 12 + 36 ------- 12 + 36 ------- 25 - 15 ------- 25 - 15 ------- 100 + 40 ------- 100 + 40 ------- 10 + 40 ------- 10 + 40 ------- 30 - 20 ------- 30 - 20 -------

13. What about decimal numbers The same rules (and poem) apply! Round 4.167 to the closest hundredths 4.167 Find your number Look right next door 4.17

14. Remember If you are asked to round to the nearest tenth…….your answer stops at the tenth place! Example: Round 42.73 to the closest tenth would be 42.7

15. Special Case! Rounding a 9 Round 2.197 to the closes hundredths Since there is a “9” in the hundredths place consider the tenth and hundredths together – 19 – do you leave it at 19 or move it to 20?

16. Round 4.95 to the closest tenth Since there is a “9” in the tenth spot consider the ones and tenths together…… should you leave it at 49 or move it to 50? 4.95 rounded to the nearest tenth is 5.0

17. Try these Round to tenths: 4.564.6 5.325.3 0.981.0 Round to hundredths 18.78418.78 9.456 9.46 9.997 10.00

18. The cafeteria is selling ice cream cones for 23¢ and ice cream sandwiches for 48¢. If Ms. Rodriguez buys an ice cream cone and an ice cream sandwich, about how much money will she spend? $1.00 70 ¢ 50 ¢ 25 ¢