Course Estimating Decimals 3-2 Estimating Decimals Course 1 Warm Up Warm Up Lesson Presentation Lesson Presentation Problem of the Day Problem of the Day

Course Estimating Decimals Warm Up Order the decimals from least to greatest , 18.7, , 9.66, 9.6, Write each in words , 18.7, , 9.076, 9.6, 9.66 three and seventy-two thousandths six and one thousand two hundred fifty-eight ten-thousandths

Course Estimating Decimals Problem of the Day Calculate your age in months. Possible answer: 11 yr 8 mo = 140 mo

Course Estimating Decimals Learn to estimate decimal sums, differences, products, and quotients.

Course Estimating Decimals Vocabulary clustering front-end estimation

Course Estimating Decimals Clustering means rounding the numbers to the same value.

Course Estimating Decimals Check It Out: Example 1 Abner wants to run, roller skate, and snow ski for 60 minutes each. About how many calories will he burn in all? (Running = calories, roller skating = calories, and snow skiing = calories) The addends cluster around To estimate the total number of calories, round each addend to Add. 570 Abner burns about 570 calories.

Course Estimating Decimals Look at the digit to the right of the place to which you are rounding. If it is 5 or greater, round up. If it is less than 5, round down. Caution!

Course Estimating Decimals Additional Example 2: Rounding Decimals to Estimate Sums and Differences Estimate by rounding to the indicated place value. A ; ones B – ; tenths Round to the nearest whole number = 12 The sum is about Round to the tenths.Align. 9.4 Subtract. – –0.3

Course Estimating Decimals Check It Out: Example 2 Estimate by rounding to the indicated place value. A ; ones B – ; tenths Round to the nearest whole number = 10 The sum is about Round to the tenths.Align. 8.4 Subtract. – –0.5

Course Estimating Decimals Compatible numbers in math means it can go into it evenly. Use for division.Remember!

Course Estimating Decimals Additional Example 3: Using Compatible Numbers to Estimate Products and Quotients Estimate each product or quotient. A  1.98 B ÷ ÷ 25 = 3 75 and 25 are compatible. So, ÷ is about 3.

Course Estimating Decimals Check It Out: Example 3 Estimate each product or quotient. A  4.98 B ÷  5 = 100 Or 22 x 5 60 ÷ 20 = 3 60 and 20 are compatible. So, ÷ is about 3.

Course Estimating Decimals Front-end estimation means to use only the whole-number part of the decimal.

Course Estimating Decimals Additional Example 4: Using Front-End Estimation Estimate a range for the sum Use front-end estimation Add the whole numbers only The whole-number values of the decimals are less than the actual numbers, so the answer is an underestimate at least 48 The exact answer of is 48 or greater.

Course Estimating Decimals Check It Out: Example 4 Estimate a range for the sum Use front-end estimation Add the whole numbers only The whole-number values of the decimals are less than the actual numbers, so the answer is an underestimate at least 58 The exact answer of is 58 or greater.

Course Estimating Decimals Check It Out: Example 4 You can estimate a range for the sum by adjusting the decimal part of the numbers. Round the decimals up to 0.5 or Add the decimal part of the numbers Add the whole-number estimate and the adjusted estimate = The adjusted decimals are greater than the actual decimal, so is an overestimate. The estimated range for the sum is from to

Course Estimating Decimals Lesson Quiz Estimate each product or quotient  ÷ The snowfall in December, January, and February was cm, cm, and cm, respectively. About how many total centimeters of snow fell during the three months? Estimate by rounding to the indicated place value ; tenths – ; nearest whole number