[R] Simple addition and subtraction doesn't work??

[Adrian Teo]

I was working on a teaching example, but came across this weird result:

> q<-c(1.6,2.6, -3.4)
> q
[1]  1.6  2.6 -3.4
> sum(q)
[1] 0.8
> sum(q)- 0.8
[1] 2.22044605e-16

Why is the result not precisely zero?

Thanks!

AT