Pronunciation: /ˈkɒn stənt/ Explain

A constant is a value that does not change.[1] It can also be a letter that represents a value that does not change.


  1. pi or π is used to represents the ratio of the circumference of a circle to its diameter. Since π always has the same value, it is a constant.
  2. In the expression 2 + y, the 2 is a constant value.
  3. In the linear equation y = m·x + b, both m and b represent values that do not change.

Commonly Used Constants

  • Zero, 0·a = 0, 0+a=a
  • One, 1·a = 1
  • Pi, the ratio of the length of the circumference of a circle to the diameter.
    pi ≈ ˜3.14159265358979323846264338327950288
  • Euler's number, the base of the natural logarithm.
    e ≈ ˜2.71828182845904523536028747135266249
  • Phi, the golden ratio.
    Phi = (1+square root(5))/2 ˜≈ 1.61803398874989484820458683436563811
  • i, the imaginary unit.
    i = square root of -1.


  1. Kornegay, Chris. Constant. 2nd edition. pg 72. Math Dictionary With Solutions: A Math Review. Sage Publications, Inc. March 6 1999. Last Accessed 8/6/2018. Buy the book
  2. Bettinger, Alvin K. and Englund, John A.. Algebra and Trigonometry. pp 53-54. International Textbook Company. January 1963. Last Accessed 8/6/2018. Buy the book

Cite this article as:

McAdams, David E. Constant. 6/29/2018. All Math Words Encyclopedia. Life is a Story Problem LLC.

Revision History

6/25/2018: Removed broken links, updated license, implemented new markup, updated GeoGebra apps. (McAdams, David E.)
1/20/2010: Added "References". (McAdams, David E.)
1/5/2010: Added "References". (McAdams, David E.)
11/21/2008: Added 'More Information'. (McAdams, David E.)
7/9/2008: Minor edit and added vocabulary link to linear equation. (McAdams, David E.)
2/13/2008: Initial version. (McAdams, David E.)

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