javascript – decimal point

Why JavaScrit is doing this, when I use calculations with decimal point?

Look:
4.4 + .4 = 4.800000000000001 — right(4.8)
3.3 + .3 = 3.5999999999999996 — right(3.6)
6.6 + .6 = 7.199999999999999 — right(7.2)

code:
num1 = parseFloat(4.4) +parseFloat(.4);

If there are something that I can do, please send me.

Thanks
Anderson