Chapter 1.2 Whole Number Estimation McDougal Littell Middle School Math Course 1 Joseph Williams Melvin E. Sine Elementary [email_address] Objective : Round to estimate with whole numbers.
Vocabulary Leading Digit – p. 13 – the leading digit of a whole number is the first digit at the left. Compatible Numbers – p. 13 – numbers that are easy to use in computations.
Estimating Sums To estimate, round each number to the same place value. Then add. 28 + 114 Round each number to the nearest ten. 30 + 110
Estimating Sums Your mother drove you 12 miles to the skate park, then 8 miles to the store. After that you drove 6 miles back home. What is an estimate of the total distance you traveled? 12 8 + 6 Round each number. 10 10 + 5 Did you get 25?
Estimating Differences To estimate, round each number to the same place value. Then subtract. 208 - 114 Round each number to the nearest hundred. 200 - 100 100
Estimating Differences You pick 92 apples. You give your cousin 48 apples. About how many apples do you have left? 92 - 48 Round each number to the nearest ten. 90 - 50 Did you get 40?
Estimating Products When you round to estimate a product, you should round the numbers to the place value of their leading digits. 191 x 11 2 00 x 1 0 = 2,000 Round both numbers to the leading digit.
Estimating Quotients 469 ÷ 59 469 ÷ 59 469 ÷ 60 Round the divisor to its leading digit. 469 ÷ 60 480 ÷ 60 Replace the dividend With a number compatible With 60 and close to 469.
Estimating Quotients Your grandfather gives you 972 pennies. You split them up between you and your 3 brothers. (4 of you altogether) About how many pennies should each of your have? 972 ÷ 4 1,000 ÷ 4 Did you get 250?