help for the first poster- a simple question

Hi, there, 
I cannot  get accurate value  for calculation.
for example:
ld<-sqrt(1*0.05*0.95*0.05*0.95)
0.05*0.95-ld=-6.938894e-18
0.05*0.95-ld==0 is False.

I met this problem in my program, how can I handle it. Thanks.


xj.