Why is Pi 3.14159 when 22/7 is 3.14285?
22/7 is NOT the real value of Pi, but just an approximation. The first value that you have(3.14159........) is the CORRECT value. 22/7 is used for simplicity ONLY. A better approximation of the value of Pi is this fraction:355/113=3.141592 and the rest of its digits are wrong. You may bring it to your teacher's attention. Good luck.
