Chapter 2 Mental Math and Estimation

  • Chapter 2

    Chapter Objective:

    * Number bonds and estimation strategies can be used to find and check sums and differences.


    Rounded - Rounded is the term used in estimating numbers to the nearest ten or hundred. Ex: 2,476 is 2,500 when rounded to the nearest hundred.

    Estimate - An estimate is a number close to the exact number. Ex: 396 is 400 when rounded to the nearest hundred.

    Reasonable - An estimated answer is reasonable when it is close to the actual answer.

    Leading Digit - The digit in a given number with the greatest place value. Ex: The leading digit for 2,475 is 2.

    Front-end estimation - Front-end estimation uses leading digits to estimate sums and differences.