Numbers: What You Think Is Not What You Get

For example:

> 0.02 / 0.00000000001 - 2000000000
[1] 2.384186e-07
> 1000 * (.15 + .3) - 450
[1] -5.684342e-14
> 0.02/0.00000000001 == 2000000000
[1] FALSE
> 1000*(.15 + .3) == 450
[1] FALSE

Yes, this is too old a topic.