W2D3-4 Rounding off numbers Grade 3 Lesson

Rounding Off Numbers PPT Grade 3

1. Rounding-off Numbers to the Nearest Tens, Hundreds, and Thousands

2. Learning Objectives: At the end of this lesson, the pupils are expected to: Round-off numbers to the nearest tens, hundreds, and thousands.

3. What is rounding-off? Round -off is to replace an exact number by another that is close to it in v alue and easier to use. For example, 52, rounded to the nearest ten is 50.

4. Memorize this poem of rounding off. Find your number. Look right next door. 4 or less, just ignore. 5 or more, add 1 more.

5. 1, 2, 3, 4 If the number next to the underlined number is 1, 2, 3, and 4, the underlined number will stay the same and the remaining digits on the right will turn into . Examples: 7 31 – 700, 6 2 – 60, 1 ,350 – 1,000

6. 5, 6, 7, 8, 9 If the number next to the underlined number is 5, 6, 7, 8, and 9, add 1 to the underlined number and all the remaining digit/s on the right will turn into . Example: 7 82 – 800, 5 6 – 60, 1 ,851 – 2,000

7. Fi nd your number Circle the number in the tens place. Round this number to the nearest tens. 5 6

8. Look right next door Look at the digit on the right side of the encircled digit. Round this number to the nearest tens. 5 6

9. 4 or less, just ignore 6 is larger than 4 so go to the next line of the poem. Round this number to the nearest tens. 5 6

10. 5 or more, add 1 more Add 1 to the encircled digit. Round this number to the nearest tens. 5 6

11. 5 or more, add 1 more After adding 1 to the 5, all numbers to the right of the 6 become 0’s. Round this number to the nearest tens. 6 0

12. Note that 56 is closer to 60 on the number line. Using Number Line 50 51 52 53 54 55 56 57 58 59 60 56

13. Fi nd your number Circle the number in the tens place. Round this number to the nearest hundreds. 9 8 6

14. Look right next door Look at the digit on the right side of the encircled digit. Round this number to the nearest hundreds. 9 8 6

15. 4 or less, just ignore 8 is larger than 4 so go to the next line of the poem. Round this number to the nearest hundreds. 9 8 6

16. 5 or more, add 1 more Add 1 to the encircled digit. Round this number to the nearest hundreds. 9 8 6

17. 5 or more, add 1 more After adding 1 to the 9, all numbers to the right of the 10 become 0’s. Round this number to the nearest hundreds. 1, 0 0 0

18. Fi nd your number Circle the number in the tens place. Round this number to the nearest thousands. 3 5, 3 2 7

19. Look right next door Look at the digit on the right side of the encircled digit. Round this number to the nearest thousands. 3 5, 3 2 7

20. 4 or less, just ignore Since 3 is less than 4, we do not change the 5. Round this number to the nearest thousands. 3 5, 3 2 7

21. 4 or less, just ignore Change the numbers to right of 5 to 0’s. Round this number to the nearest thousands. 3 5, 0 0 0

22. 139 45 282 97 842 Exercise 1: Round these number to the nearest tens. 140 50 280 100 840

23. 2,139 19,745 282 3,197 842 Exercise 2: Round these number to the nearest hundreds. 2,100 19,700 300 3,200 800

24. 2,839 19,445 8,982 43,197 5,542 Exercise 3: Round these number to the nearest thousands. 3,000 19,000 9,000 43,000 6,000