Changes

The value of <big><math>\pi</math></big> is an [[irrational number]]; which means that it cannot be fully expressed as a fraction or a decimal (regardless of the number of digits used).  

The value of <big><math>\pi</math></big> is an [[irrational number]]; which means that it cannot be fully expressed as a fraction or a decimal (regardless of the number of digits used).  

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.  

The approximate value of 3.14159 is precise enough for almost all ordinary purposes; it can, for example, be used to calculate the circumference of a circle of the size of the Earth with an error of only about 110 feet.  

For rough purposes, the fraction 22/7 (= 3.142857...) is sometimes used.

For rough purposes, the fraction 22/7 (= 3.142857...) is sometimes used.