Estimation

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Estimation & Computation The goal of this map is to cover the important components of estimation & computation. You will also find resources that can be used in a K-6 setting.

Assignment Resources

More Estimation Worksheets

Estimation Worksheets

Computational Estimation - The process of finding an answer that is relatively close to the real answer.

Clustering - In some addition problems, the numbers cluster around a common number. Find the common number and multiply by the number of addends. For example: 24, 31, 37, 28 can all be compared to 30. So, we would turn this into 30 X 4.

Front-end estimation - Use the left most digit and pretend all the other digits to the right are zeros. For example: 718-309 can be replaced with 700-300.

Substitution of Compatible Numbers - Replacing some or all of the numbers in a problem with numbers that are easier to compute mentally. For example: 2,479-222 can be replaced by 2,480-220.

Rounding - The process of a number or numbers in a problem with the closest multiple of 10, 100, 1,000, and so on. First find the halfway point between the multiples. Anything below the half way point rounds down while anything above it rounds up. For example: 423 would round down to 420 because the 3 is below 5. 435 would round to 440 because the 5 causes you to round up.

Estimation & Computation Lesson Plan Example

Place Value - The numerical value a digit has because of it's position in a number.

Wonderful video introducing place value to students

This website has a breakdown of numbers and their place value which includes visual aides.

Mental Computation - The process of finding the exact answer to a problem mentally, without any outside supports. For example paper, pencil, calculator...

Use Compensation Technique - First substitute compatible numbers to make the computation easier to deal with. Then, adjust the answer to compensate for the change you made. For example: 4.99+7.95= 5+8=13 Now compensate for the extra: 13-.06=12.94

Break Apart Numbers Technique - Break numbers in computations up into more reasonable easy to work with numbers. For example: 264 can be broken apart to equal 100+100+60+4

Choose Compatible Numbers Technique - Look for compatible number patterns that can be solved together easily. Then continue computing like number patterns. For example, numbers that create multiples of 10 or 100. Example: 37+20+243+200= 37+20=57, 243+200=443, 443+57= 500

Count Back Technique - Like the Count On Technique, this method is best when used with the numbers 1, 2, or 3. Select the larger number first, then subtract by intervals until you have used the second number. For example: 430-3= 430, 429, 428, 427

Count On Technique - Method for adding when one of the addends is 1, 2, or 3. Select the larger addend first, then add by intervals until you have used the second addend. For example: 65+30= 65, 75, 85, 95

Counting On and Back Technique

Teaching Mental Math Video