Rounding Decimals Unit 3.2 Pages 104-107
Order the numbers from LEAST to GREATEST? Warm Up Problems Order the numbers from LEAST to GREATEST? 18.74, 18.7, 18.47 9.06, 9.66, 9.6, 9.076 3.072 6.158 18.47, 18.7, 18.74 9.06, 9.076, 9.6, 9.66 Three and seventy two thousandths Six and one hundred fifty eight thousandths Write in words
Estimating Decimals. Objective: Students will be able to estimate decimal sums, differences, products and quotients by clustering, using place value, grouping and using front/back end estimation.
Wholes Parts of the Whole A decimal helps us to see what numbers are WHOLE numbers, and what numbers are PARTS OF THE WHOLE. Wholes Parts of the Whole
Definitions Clustering: Rounding numbers to the same value (amount). Front-End Estimation: Use the whole numbers in the decimals to estimate values (amounts).
Let’s review some definitions that we should already know. Sum Difference Product Quotient Addition Subtraction Multiplication Division
We use decimal estimation in real word situations? Can you think of any?
We will be solving equations with decimals using a few different strategies: Place Value Front End Comparable Numbers Clustering
Estimate numbers with decimals by rounding to the indicated place value. Place Value ONES Look at the digit to the right of your place value. If it is a 5 or greater round up one number. If it is less that 5 round down by adding zero’s. 3.92 + 6.48 3.92 + 6.48 3.92 + 6.48 4.00 + 6.00 4 + 6 = 10
#2. Estimate numbers with decimals by rounding to the indicated place value. Place Value tenths 2.746 – 0.866 Look at the digit to the right of your place value. If it is a 5 or greater round up one number. If it is less that 5 round down by adding zero’s. 2.7 – .9 = about 1.8
#3. Estimate numbers with decimals by rounding to the indicated place value. Place Value ones 6.735 + 4.9528 Look at the digit to the right of your place value. If it is a 5 or greater round up one number. If it is less that 5 round down by adding zero’s. 7.0 + 5.0 = about 12
We will be solving equations with decimals using a few different strategies: Place Value Front End Comparable Numbers Clustering
When numbers are close to the same amount, you can use Someone who weighs about 90 pounds can burn the following calories: Clustering Activity Calories Estimation Bicycling 198.45 Playing Ice Hockey 210.60 Rowing 224 Water Skiing 194.4 200.00 When numbers are close to the same amount, you can use clustering: changing all amounts to same value.
Ella will run about _____ total miles . #1. Ella runs three days a week. She ran 3.62 miles on Monday, 3.8 miles on Wednesday, and 4.3 miles on Friday. About how any miles did she run on last week? Clustering Days of the Week Miles Estimation Monday 3.62 Wednesday 3.8 Friday 4.3 4.00 Ella will run about _____ total miles . 12
Estimate Each Product or Quotient Compatible Numbers Compatible numbers are close to the numbers that are in the problem, and can be helpful when you are solving estimations using MENTAL MATH. 26.76 x 2.93 26.76 x 2.93 25 x 3 about75
Estimate Each Product or Quotient Compatible Numbers Compatible numbers are close to the numbers that are in the problem, and can be helpful when you are solving estimations using MENTAL MATH. 42.64 16.51 42.64 16.51 40 / 20 about2
Estimate Each Product or Quotient #6 Estimate Each Product or Quotient Compatible Numbers Compatible numbers are close to the numbers that are in the problem, and can be helpful when you are solving estimations using MENTAL MATH. 38.92 4.06 __ /__ About _______
Estimate Each Product or Quotient #7 Estimate Each Product or Quotient Compatible Numbers Compatible numbers are close to the numbers that are in the problem, and can be helpful when you are solving estimations using MENTAL MATH. 14.75 x 7.89 __ /__ About _______
Front and Back End Estimation When using the Front End Estimation Strategy we look at the WHOLE number, in front of the decimal and estimate for that number before adding or subtracting the amounts. Front and Back End Estimation 9 22 + 8 39 9.99 22.89 + 8.30
Front and Back End Estimation When using the Back End Estimation Strategy we look at the WHOLE number, in back of the decimal and estimate for that number before adding or subtracting the amounts. Front and Back End Estimation 9.99 22.89 + 8.30 1.00 + .50 2.50
We can now take the two amounts, add them together and find the 9.99 22.89 + 8.30 We can now take the two amounts, add them together and find the RANGE For the sum. Front and Back End Estimation 39 + 2.50 The range is 39 to 41.50
Find the range for each sum. #9. Find the range for each sum. Front and Back End Estimation 8.00 31.00 7.00 46.00 7.8 31.39 + 6.95 1.00 .40 2.40 The range is about 46 to 48.40
Find the range for each sum. #10. Find the range for each sum. Front and Back End Estimation 14.00 5.00 22.00 41.00 14.27 5.4 +21.86 .30 .40 1.00 1.70 The range is about 41 to 42.70
12-26 12-19 3.2 Homework Page 106-107 Due: Thursday Mrs. Saucedo’s class 12-19
Round to the tenth place value Round to the nearest whole place 3.0744 + 1.352 7.305 – 4.1268 3 4.5 Estimate each product or quotient Estimate each product or quotient 6.75 x 1.82 10.5 3.42 14 9