Make reasonable estimates of fraction and decimal sums and differences, and use techniques for rounding.
Remarks: Use a variety of strategies for estimating sums and differences of fractions and decimals including benchmark fractions and decimals, and rounding techniques.
Example: Students know that 7/8 + 11/12 is close to 2, because 7/8 and 11/12 are each close to 1.
Example: Use appropriate benchmarks to estimate the difference between 1.801 and 1.239, be sure to show all work.
Possible Answers: 1.75 – 1.25 = 0.5 OR 1 ¾ - 1 ¼ = ½
Example: Use an appropriate strategy to estimate the total cost for a shirt that costs $5.89 and a pair of shorts that costs $6.34, justify your answer.
Possible Answers: If I round each of the cost to the nearest tenth, then $5.90 + $6.30 = $12.20. OR Since one costs slightly less than $6 and the other costs slightly more than $6, I would estimate the total cost to be 2 × $6 = $12.
Subject Area: X-Mathematics (former standards - 2008)
Body of Knowledge: Algebra
Idea: Level 2: Basic Application of Skills & Concepts
Big Idea: BIG IDEA 2
- Develop an understanding of and fluency with addition and subtraction of fractions and decimals.
Date Adopted or Revised: 09/07
Date of Last Rating: 06/07
Status: State Board Approved - Archived