in my math book there's written pie=3.1416 but when i calculate 22/7 the answer is 3.142857.....why like that?

Answer 1

22/7 is only an approximation of pi using whole numbers.

Sometimes, using the 22/7 version makes pi easier to work with, as it gets rid of decimals from the equation when you need to eliminate symbols altogether.

Answer 2

Pi is a irrational number, for expedience, it's written as 3.1416 But as you say when you calculate Pi it comes out at 3.142857 excetra. But three places of decimals is sufficient for area or circumference maths so pay it no mind. Have a good day.

Answer 3

An even more accurate approximation is 355/113. Using the theory of continued fractions it can be proved that there is in fact an infinite sequence of better and better rational approximations with relatively low denominators. But there is no ultimate way of expressing pi as a ratio of two whole numbers - this is because pi is a so-called irrational number: its decimal expansion contains infinitely many figures with no repetition from some point onwards (and in fact no easily recognized patterns of any kind).

Answer 4

22/7 is the approximation of value of pie to represent in fraction form. The value 3.1416 is the actual value of pie.

Answer 5

Because Pi is not equal to 22/7. It is an irrational number which cannot be reduced to a fraction of whole numbers.

Answer 6

Pi is an irrational number, this means that the decimal places go on forever. 22/7 is a crude estimate

It starts 3.141592653 ... and carries on forever. So if you write Pi to a certain number of decimal places it is an approximation.

Answer 7

Because π is an 'irrational' number. That just means that it cannot be written -exactly- as the quotient of two integers. If you round 3.14159265....... to the nearest 100'th, they're the same. And how often do you really need more than 3 significant digits? ☺

Doug

Answer 8

Your calculation is incorrect. It should be 3.1415927.

Answer 9

http://www.youtube.com/watch?v=BUNDfyy2f5M