how to prove sum of probabilities to be one in R?

Hi Dear

I am facing a floating-point problem related to the sum of probabilities.
It is really difficult to prove that sum of probabilities is 1 because of
some minor differences. The MWE is as follows.

p1=0.99999999
p2=0.00000000003> p1+p2==1[1] FALSE

The sum of probabilities is approximately 1. The difference from 1 is
1-p1-p2 =  9.97e-09, that is very small. I need to apply the sum of
probabilities conditions in my many functions. But execution is halted
because of floating point.

Could anyone please guide about that?

Thank you

Regards

Shaami