Question

Is 3.142857 a rational number

Answer 1

A rational number is any number that can be expressed as the ratio between two integers; i.e. by division or as a fraction. In this case:

`3.142857=(3,142,857)/(1,000,000)`

Be careful here.
`(3,142,857)/(1,000,000)` is very close to
`(22)/(7)` (a common approximation for pi) but
`(22)/(7)` does not terminate, it repeats while 3.142857 does terminate. Both are rational but they are not equal.

Answer 2

If you're talking about just the decimal, then yes it is.
If you're talking about 22/7, then it still is.
But if you're talking about pi, then it isn't rational.