2. Confidential 1 OUR LESSON : Rounding and Estimating

3. 2 Use > or < to compare these numbers. 1.) 2.35___ 2.33 2.) 3.13___ -3.13 3.) 5.05___ 5.00 4.) 1.01 ___ 1.10 5.) -0.01 ___ -0.001 WARM-UP:

4. Confidential 3 Lets review what we did in the last lesson Decimals are numbers which have dot (decimal) in it Digits of the number to the left of the decimal point represent the whole number Digits on the right of the point are decimal fractions. If there is no whole number, the decimal will begin with a zero in the units position. Digits after the decimal point are read individually

5. Confidential 4 Lets take an example 523, 52.3, 5.23, 0.523 These three numbers above have the same three digits, in the same order, yet they are very different. 523 is a whole number and would be read as five twenty three. The second number has a decimal in it and would be read as fifty two point three 5.23 would be read as five point two three 0.523 contains no whole number in it so will be read as point five two three

6. Confidential 5 We can also compare two decimals by comparing the digits in each place-value position. T O. T H TH 4. 6 4 4. 5 2 Start at the left and compare the digits in each place- value position. In the ones place, the digits are the same In the tenths place, 6 > 5, so, 4.64 > 4.57 Comparing Decimals

7. Confidential 6 We are familiar with Decimals and their place-value positions. So now will learn how rounding of decimal numbers is done to get to the nearest approximate whole number. It is a kind of Estimation that we make. We use Rounding to estimate time, money, distances etc. Lets Get Started Rounding and Estimation

8. Confidential 7 Lets try to understand the importance of this concept with this example If our supermarket bill totals to $52.29 we would give $52 at the counter. However if the total was $52.85 we would be required to give $53

9. Confidential 8 Rules of Rounding of Decimals We can round decimals to any place value. Find the place value you want (the "rounding digit") and look at the digit just to the right of it. If that digit is less than 5, do not change the rounding digit but drop all digits to the right of it. If that digit is greater than or equal to five, add one to the rounding digit and drop all digits to the right of it.

10. Confidential 9 1) 28,4582) 28,9253) 28,512 28,000 29,000 29,000 So lets see how we round these numbers to the nearest thousand. The rounding Digits are in Red The digit to their right is in Yellow

11. Confidential 10 Let us take another example Round 73,852 to the nearest 1. Ten-thousand. 2. Thousand. 3. Hundred. 4. Ten. 70,000 74,000 73,900 73,850

12. Confidential 11 Another way that we can round the decimals is to their N earest Fractions Lets round 625.3682 to the nearest 1.) Tenth 2.) Hundredth 3.) Thousandth 4.) Last Digit 625.4 625.37 625.368 625.3682

13. Confidential 12 Now you try some ! 1.) 325.34 To the nearest Hundred 2.) 48.722 To the nearest Ten thousand 3.) 43.381 To the nearest Hundredth 4.) 60.528 To the nearest Tenth

14. Confidential 13 Estimating with Decimals Estimate by Rounding Example 23.485 – 9.757 23.485  23 9.757  10 23.485 – 9.757 is about 23 -10 = 13 The difference is about 13

15. Confidential 14 Your Turn! Estimate 43.9 x 37.5 Estimate 6.43 + 2.17 + 9.1 + 4.87

16. Confidential 15 Lets see how well you have grasped your concept today Compare and arrange these decimals from least to the greatest after rounding them to the tenth. 82.36, 82.81, 61.83, 61.49, 65.88

17. Confidential 16 Break Time!!

18. Confidential 17 GAME TIMEGAME TIME click here to play a Game

19. Confidential 18 1)Write three decimals that would round off to 82.356

20. Confidential 19 2.)The Grocery bill for Mrs. Johnson is $282.31. What amount is required to be paid by Mrs. Johnson if the bill is rounded to the nearest dollar

21. Confidential 20 3) The exact distance from the school to the house for five students is given as under 4.53, 6.12, 8.61, 1.28, 3.81 The teacher has asked them to write the distance in a form which has space of only one digit after decimal. What should each student write there?

22. Confidential 21 1.Round each number to the underlined place-value position a)46.124 b)29.915 c)331.98 2.Round each number to the place indicated. a)0.219; hundredth b)15.552; tenth c)9.6; unit 3.Estimate by rounding 432.87 ÷ 8.9 4.Estimate by rounding 23.84 + 12.13 Assessment

23. Confidential 22 Let's Review what we have learnt today Find the place value you want and look at the digit just to the right of it. 5,834 To the nearest thousandth If that digit is less than 5, do not change the rounding digit but drop all digits to the right of it. 8 is greater than 5 If that digit is greater than or equal to five, add one to the rounding digit and drop all digits to the right of it so here we get6000

24. Confidential 23 Remember We can also round the decimals to their nearest Fractions in the same way Lets round 83. 461 to the nearest tenth place 83.4 6 1 The place value number is 4 and number to its right is 6. 6 Is greater than 5 so We round the number to 83.5

25. Confidential 24 You had a GREAT lesson today! Be sure to practice what you learned!