2. ESTIMATION

3. Estimating Guess how many? There are 20 pens

4. Estimating Guess how many? There are 15 kites

5. Estimating Guess how many? There are 25 pencils

6. Estimate the number of bricks used to build this portion of a chimney.

7. You´re answers vary because you are estimating. It is when you make a guess of what you think the answer might be close to, such as when you estimate how many bricks were used to build the chimney.

8. ROUNDING

9. Rounding two-digit numbers 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 th closer to 30 than to 20.

10. Rounding three-digit numbers 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

11. 20 26 30 26 is closer to 30 than to 20. 52060050 0 520 is closer to 500 than to 600.

12. 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

13. Estimating differences 250 - 110 ------ - 250 - 110 ------ - First, round all the numbers using the RULES FOR ROUNDING. Then, perform the operations. 300 - 100 ------- 300 - 100 ------- 200 200

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

15. Rounding Whole Numbers Through Millions By Mr. Bales

16. Objective »You will be able to round whole numbers through the millions to the nearest 10, 100, 1,000, 10,000, or 100,000

17. Problem »Each year immigrants from around the world come to the United States. In 2003, California schools welcomed 175,090 immigrant students. »What is 175,090 rounded to the nearest thousand?

18. How To Round »Let’s look at this number 175,090. »First, underline the place value that you want to round. »Then, look at the digit to the right. If the digit is 4 or less, the digit in the rounding place stays the same. »If the digit to the right is 5 or more. The digit in the rounding place increases by one. »Last, change all the digits to the right of the rounding place to zero.

19. Game Time!! »Round to the nearest hundred »71,105 »654,354 »678,947 »Round to the nearest ten thousand »1,256,876 »23,786,983 »Round to the nearest hundred thousand »234,654,899 »3,853,216 »Round the nearest billion »6.834,652,985 »87.476,634,321 »Round to the nearest hundred thousand »234,654,899 »3,853,216 »Round the nearest billion »6.834,652,985 »87.476,634,321

20. Your turn!

22. Estimate each product, addition and subtraction. 1. 62 X 82 2. 59 X 48 3. 74 X 302 4.324587-52418 5. 4681+9284 6. 31,877 – 12,794 7. 11,284,788 + 835,785,022 5. 4681+9284 6. 31,877 – 12,794 7. 11,284,788 + 835,785,022