1.2 Estimate with Whole Numbers (p.18-21)

• An estimate is a value close to the exact amount
• An estimate should be easier to find than an exact number
• An estimate is quick way to get an idea of about "how much"

I. Ways to Estimate

1. Estimate by ROUNDING: Choose a place to round to-- use the digit to right of the chosen place-- if the digit to the right is 5 or more "raise the score"-- if the digit to the right is 4 or less "let it rest"--numbers to the right of the place being rounded become zeros. If you are have trouble rounding watch the video at this from Math Playgroud
   


2. Estimate by CLUSTERING (when adding): When adding values that are close together, use one number to represent the values and then multiply that number by the quantity of values that have been clustered together.


3. Estimate by using CONVENIENT NUMBERS (when dividing): Use a value close to the original number that can more easily be divided to get an estimate.

II. Types of Estimates

1. Underestimating: When the estimate is less than the exact number - happens when you turn the original number(s) into a smaller value.
2. Overestimating: When the estimate is more than the exact number - happens when you turn the original number(s) into a larger value.

Here is Wikianswers

Practice what you learned about estimation at this site