Changes

<big><math>\pi</math></big> is an [[irrational number]]; this means that it cannot be expressed as a fraction, and (therefore) cannot be expressed exactly as a decimal no matter how many decimal places it is carried out to.  

<big><math>\pi</math></big> is an [[irrational number]]; this means that it cannot be expressed as a fraction, and (therefore) cannot be expressed exactly as a decimal no matter how many decimal places it is carried out to.  

The value of <big><math>\pi</math></big> is approximately 3.14159 in decimal. This value is precise enough for almost all ordinary purposes; it can, for example, be used to calculate the circumference of the Earth with an error of only 350 feet.  

The value of <big><math>\pi</math></big> is approximately 3.14159 in decimal. This value is precise enough for almost all ordinary purposes; it can, for example, be used to calculate the circumference of the Earth with an error of only about 110 feet.  

For rough purposes, the fraction 22/7 (= 3.14285...) is sometimes used. 355/113 is accurate to six places.

For rough purposes, the fraction 22/7 (= 3.14285...) is sometimes used. 355/113 is accurate to six places.