JM


 * Estimating Sums and Differences**

When you estimate sums and differences, you can use the same methods you would use for whole numbers.


 * Examples**

For easier adding, round each number to the nearest ten: 70 .7 -> 70 __+ 78 .5__ -> __+ 80__

//Clustering// As you can see, the addends are clustered around the number 70. So that is the number we use in the problem. 70 70 70 __+70__ 280 //Front-end estimation//  3 .6 __+__5 __.9__ 8 Here is a short [|video]. For more examples, go to [|here]
 * **Month** || **Hours Worked** ||
 * May || 72.50 ||
 * June || 68.50 ||
 * July || 69.75 ||
 * August || 71.75 ||


 * Other kinds of Estimation**

One of the many other kinds of estimation there is out there is called front-end estimation. When using front-end estimation, you add or subtract the first digits. Then, repeat the step in the next value positions.

Also, there is something else called clustering. Clustering is another form of estimation that you use when all of the addends are close to the same number.

Links: http://www.teachertube.com/index.php http://www.glencoe.com/sec/math/prealg/mathnet/pr01/pdf/0502a.pdf http://www.algebra-online.com/estimating-sums-differences-mixed-numbers-1.htm