Front end estimation is adding two or more numbers to get an estimated sum total. In front end estimation, the numbers are always rounded off to the lowest round number. Look here
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The last digit given for any measurement is the uncertain or estimated digit. It is
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If you are measuring with a ruler marked in mm, the '8' is the number of mm. The '2' can be estimated if you look closely between the millimeter marks.
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1. Rearrange the sum or difference problem so that the missing digit is isolated on one side of the equation. For example, if your equation is "x  9 = 7" where "x&
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