1. 99 21 12 57 Chris Clements Rounding To the nearest 10

2. Learning Objective:

3. Rounding Rounding is used to approximate or estimate. Numbers are usually rounded to the nearest 10, 100, 1000, 10 000, 100 000 or even a 1, 000 000. Decimals can also be rounded, usually to the nearest tenth, hundredth, thousandth…

4. Rounding whole numbers Negative numbers are also whole numbers e.g. -1, -2, - 3… Whole numbers (also called integers) are counting numbers e.g. 1, 2, 3, 4… Decimals are not whole numbers e.g. 0.4, 7.4, 2.36, 7.32… Fractions are not whole numbers e.g. ½ 2 ¾, 25 ¼ … Decimals are not whole numbers e.g. 0.4, 7.4, 2.36, 7.32…

5. Rounding to the nearest 10 When rounding to the nearest 10 there are three main things to remember; 1) Identify the units digit. 2) If the units digit is a 1, 2, 3 or 4 we round down. 3) If the units digit is a 5, 6, 7, 8, or 9 we round up. continued When rounding to the nearest 10 there are three main things to remember; 1) Identify the units digit. 2) If the units digit is a 1, 2, 3 or 4 we round down. 3) If the units digit is a 5, 6, 7, 8, or 9 we round up. Steps to success When rounding to the nearest 10 there are three main things to remember; 1) Identify the units digit. 2) If the units digit is a 1, 2, 3 or 4 we round down. 3) If the units digit is a 5, 6, 7, 8, or 9 we round up.

6. Lets see how well you are doing. REMEMBER Step 1! continued 1) Identify the units digit.

7. Onto the next step. Can you remember it? continued 2) If the units digit is a 1, 2, 3 or 4 we round down. continued

8. Now for the final step. Can you remember it? continued 3) If the units digit is a 5, 6, 7, 8, or 9 we round up. continued

9. Lets have a go at these; continued

11. Activity

12. Plenary At a builders yard bricks are sold in packs of ten. Jim wants 87 bricks to fix a broken wall. How many bricks must he buy? If Jim went to buy 14 more bricks, what would happen if he rounded down to 10 and bought one more pack? Round 356 to nearest 10 Round 2732 to nearest 10 What makes these more difficult? 90 bricks (9packs of 10) He would be 4 bricks short and will need to go back again! 360 2730 He would be 4 bricks short and will need to go back again!