1. Rounding To the nearest 100

2. Rounding In this lesson we are looking at rounding numbers to the nearest 100. Rounding Rounding is used to approximate or estimate.

3. Rounding whole numbers Can you remember how to round numbers to the nearest 10? Identify the units digit. If the units digit is a 1, 2, 3 or 4 we round down. If the units digit is a 5, 6, 7, 8, or 9 we round up.

4. continued There is a similar pattern for rounding numbers to the nearest100 1) Identify the tens digit.

5. Onto the next step. continued 2) If the tens digit is a 0, 1, 2, 3 or 4 we round down to the nearest 100. continued 510520530540550560570580590 Is it closer to 500 or 600? Is it closer to 400 or 500? 410420430440450460470480490 Can you see that the units digit is not important when rounding numbers to 100?

6. Onto the final step. continued 3) If the tens digit is a 5, 6, 7, 8 or a 9 round up to the next hundred. continued 510520530540550560570580590 Is it closer to 500 or 600? Is it closer to 600 or 700? 610620630640650660670680690 Remember if a number ends in -50, although it is exactly halfway between the two hundred values we still round up!

7. Lets have ago at rounding to the nearest 100. continued 310320330340350360370380390 Is it closer to 300 or 400? 610620630640650660670680690 Is it closer to 600 or 700? 710720730740750760770780790 Is it closer to 700 or 800?

8. And more… 110120130140150160170180190 Is it closer to 100 or 200? 810820830840850860870880890 Is it closer to 800 or 900? 910920930940950960970980990 Is it closer to 900 or 1000?

9. continued Now without the number line!

10. Plenary Match these numbers to the nearest 100. 428700 342100 712400 51300 170 490 320 420 390 Choose 2 cards that when added together round to 500. 170 and 320 = 490

11. Rounding to the nearest 10,100 -Miniwbs -Markers -LET’S GO!

12. Round 19 to the nearest 10

13. Round 22 to the nearest 10

14. Round 83 to the nearest 10

15. Round 219 to the nearest 100

16. Round 342 to the nearest 100

17. Round 57 to the nearest 10

18. Round 743 to the nearest 10

19. Round 841 to the nearest 100

20. Round 44 to the nearest 10

21. Round 99 to the nearest 10

22. Round 350 to the nearest 100

23. Round 454 to the nearest 100

24. Round 516 to the nearest 10

25. Round 188 to the nearest 10

26. Round 975 to the nearest 100

27. Round 9709 to the nearest 100

28. Round 1902 to the nearest 10

29. Round 371 to the nearest 10

30. Round 3761 to the nearest 100

31. Round 8555 to the nearest 100

32. Round 1100 to the nearest 100

33. Round 8401 to the nearest 10

34. Homework STP 7A Pg 13 Exercise 1H 11-20 Round to the nearest 100