2. Rounding and Estimating Rounding a whole number means approximating it. Section 1.4

3. 23 rounded to the nearest ten is 20. 48 rounded to the nearest ten is 50. 15 rounded to the nearest ten is 20. 102015405048203023 2 Martin-Gay, Prealgebra, 5ed

4. Rounding Whole Numbers to a Given Place Value Step 1. Locate the digit to the right of the given place value to be rounded. 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, keep the digit in the given place value and replace each digit to its right by 0. 3 Martin-Gay, Prealgebra, 5ed

5. Making estimates is often the quickest way to solve real-life problems when their solutions do not need to be exact. 4 Martin-Gay, Prealgebra, 5ed

6. Helpful Hint Estimation is useful to check for incorrect answers when using a calculator. For example, pressing a key too hard may result in a double digit, while pressing a key too softly may result in the number not appearing in the display. 5 Martin-Gay, Prealgebra, 5ed