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

2. Vocabulary Rounding redondear* Estimation estimación*
Approximately aproximadamente*
Nearest más cercano*
Hundreds centenas
Place value valor de posición
Differences diferencias*
Almost casi
Close to cerca a
Estimation estimación*
About how many* aproximadamente cuantos
Tens decenas
Thousands miles
Sums sumas*
Reasonable razonable
Nearly casi

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

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

5. 26 is closer to 30 than to 20. 20 26 30
520 is closer to 500 than to 600.
500
520
600

6. 10 + 10 ------- 12 + 8 ------- 20 Estimating sums
First, round all the numbers using the RULES FOR ROUNDING
Then, perform the operations. 20

7. Estimating differences
First, round all the numbers using the RULES FOR ROUNDING
Then, perform the operations. 20

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

9. Review the vocabulary Rounding redondear Approximately aproximadamente
Nearest más cercano
Hundreds centenas
Place value valor de posición
Differences diferencias
Almost casi
Close to cerca a
Estimation estimación
About how many aproximadamente cuantos
Tens decenas
Thousands miles
Sums sumas
Reasonable razonable
Nearly casi

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

11. Practice rounding sums and differences

12. TAKS Preparation Sample Questions

13. 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 ¢