Pronunciation: /əˈprɒk səˌmeɪt/ Explain

To approximate is to find a number close to a real number.[1] Since irrational numbers can not be exactly stated as a decimal, an approximation is used. For example, the value of π is approximately 3.14159. The symbol for writing 'approximately equal to' is ''. For example, π ≈ 3.14159.

One method of approximation is called interpolation. The study of approximation in mathematics is called approximation theory which is a branch of numerical analysis.


  1. Lambert, P.A., M.A.. Computation and Mensuration. pg 1. MacMillan and Company. 1907. Last Accessed 8/6/2018. Buy the book

Educator Resources

  • Estimate and Measure. NASA Connect. 2/18/2010.
  • Serving Size Activity. NASA Connect. 2/18/2010.

Cite this article as:

McAdams, David E. Approximate. 6/14/2018. All Math Words Encyclopedia. Life is a Story Problem LLC.

Revision History

6/14/2018: Removed broken links, updated license, implemented new markup. (McAdams, David E.)
1/6/2010: Added "References". (McAdams, David E.)
10/10/2008: Added paragraph on interpolation. Expanded 'More Information' (McAdams, David E.)
4/18/2008: Initial version. (McAdams, David E.)

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