Each digit in a number has a value that depends on its place in that number i.e. its place value Four hundred and fifty two point nine four five For example: 452.945 400 Hundreds 100 s 50 tens 10 s 2 units 1s 0.9 tenths 1/10 s 0.005 0.04 hundredths thousandths 1/1000 s 1/100 s Imagine if I put a 5 at the beginning of the number. What would each number represent? 5452.495 Unit 3: Decimals Today: Place Value and Ordering 02/10/17 LO’s: I can write decimals and understand place value I can order decimals Starter – What goes with these to make 1? 0.5 0.6 0.2 0.25 What goes with these to make 10? 2.4 4.8 7.3 1.9 8.41 3.82 Ordering Decimals 0.2 0.25 0.52 0.34 0.355 0.02 1.25 Ordering Decimals 0.2 0.25 0.52 0.34 0.355 0.02 0.200 0.250 0.520 0.340 0.355 0.020 Ans: 0.02 0.2 0.25 0.34 0.355 0.52 1.25 1.25 1.25 Unit 3: Decimals Today: Place Value and Ordering 2/10/17 LO’s: I can add / subtract decimals Starter – Order these decimals from smallest to largest 2. 3. 4. 5. 0.94 4.71 3.65 0.3 0.91 3.65 3.69 0.35 0.97 3.83 3.6 0.5 0.9 4.91 3.06 0.53 0.89 3.15 3.46 0.355 0.8 4.09 3.4 0.03 0.907 3.5 3.1 0.61 2. 3. 4. 5. 2. 3. 4. 5. 0.94 4.71 3.65 0.3 0.8 3.15 3.06 0.03 0.91 3.65 3.69 0.35 0.89 3.5 3.1 0.3 0.97 3.83 3.6 0.5 0.9 3.65 3.4 0.35 0.9 4.91 3.06 0.53 0.907 3.83 3.46 0.355 0.89 3.15 3.46 0.355 0.91 4.09 3.6 0.5 0.8 4.09 3.4 0.03 0.94 4.71 3.65 0.53 0.907 3.5 3.1 0.61 0.97 4.91 3.69 0.61 Adding and Subtracting Decimals “Star questions” – CHALLENGE 11.57 – 9.82 – 2.53 26.5 + 1.85 +208.3 Unit 3: Decimals 16/10/17 Rounding LO’s: I can round to 1dp and 2dp Starter – Can you round these numbers to the nearest 10? 74 23 35 67 19 123 288 423 194 198 694 1148 2357 1484 3495 Rounding Decimals Find your number. Look right next door. 4 or less, just ignore. 5 or more, add 1 more. Find your number. Look right next door. 4 or less, just ignore. 5 or more, add 1 more. Rounding Decimals Round these to the nearest 1 decimal place: 1. 5.349 2. 14.23 3. 8.62 4. 472.450 Round these to the nearest 2 decimal places: 5. 13.983 1. 5.349 6. 6.544 2. 14.233 7. 93.15 3. 8.6251 8. 9.897 4. 472.410 9. 645.07 5. 13.9839 10. 32.545 Extension PRACTICE PRACTICE PRACTICE! PRACTICE PRACTICE PRACTICE! two decimal places: B) Rounding to decimal places Complete this table: to the nearest whole number to 1 d.p. to 2 d.p. to 3 d.p. 63.4721 63 63.5 63.47 63.472 87.6564 88 87.7 87.66 87.656 149.9875 150 150.0 149.99 149.988 3.54029 4 3.5 3.54 3.540 0.59999 1 0.6 0.60 0.600 Rounding to decimal places Complete this table: to the nearest whole number 63.4721 87.6564 149.9875 3.54029 0.59999 to 1 d.p. to 2 d.p. to 3 d.p. EASY MODERATE CHALLENGING CHALLENGING