What is a benchmark fraction?

Answer 1

Benchmark fractions are common fractions that you can judge other numbers against. Normally, 1/4, 1/2, 3/4, and often 1/10 (because of its relationship with decimals) are refered to as benchmark fractions.

Estimation is a perfect example of how a benchmark fraction is used. If you are measuring the length of an object, and it is 3 9/32 inches, you are most likely to say 3 1/4 inches, instead of rounding down to 3 inches, or getting a more precise measurement of 3 9/32.

By far the most common benchmark is 1/2. In rounding a number, 1/2 is the difference between going up to the next number, or rounding off to the last number. In many cases, problems that use the standard measurement system will ask that an object be measured to the nearest 1/2 unit (1/2 inch, 1/2 cup) This is not as common with metric units, since they are a base 10 system, but you may see some 1/2 liter or 1/2 kilometer measurements.

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