Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Chapter 1 The Whole Numbers

Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. 1.5 Rounding and Estimating

Martin-Gay, Developmental Mathematics, 2e 33 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Rounding Whole Numbers Rounding a whole number means approximating it. 26 is closer to 30 than 20, so 26 is rounded to the nearest ten is is closer to 50 than 60, so 52 is rounded to the nearest ten is 50.

Martin-Gay, Developmental Mathematics, 2e 44 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Rounding Whole Numbers 25 is halfway between 20 and 30. It is not closer to either number. In such a case, we round to the larger ten, that is, to 30.

Martin-Gay, Developmental Mathematics, 2e 55 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Rounding Whole Numbers Rounding Whole Numbers to a Given Place Value Step 1: Locate the digit to the right of the given place value. Step 2: If this digit is 5 or greater, add 1 to the digit in the given place value and replace each digit to its right by 0. Step 3: If this digit is less than 5, replace it and each digit to its right by 0.

Martin-Gay, Developmental Mathematics, 2e 66 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Examples 1. Round 568 to the nearest ten Round 278,362 to the nearest thousand. 278, Round 248,982 to the nearest hundred. 249,000

Martin-Gay, Developmental Mathematics, 2e 77 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Estimating Sums and Differences Example Estimate the sum by rounding each number to the nearest hundred.

Martin-Gay, Developmental Mathematics, 2e 88 Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall. Solving Problems by Estimating Example Jared Nuss scored 89, 92, 100, 67, 75 and 89 on his biology tests. Round each score to the nearest ten to estimate his total score.