with(Tolerances):

Warning, these protected names have been redefined and unprotected: `*`, `+`, `-`, Ei, FresnelC, FresnelS, GAMMA, LambertW, Psi, Zeta, `^`, abs, arccos, arccosh, arccot, arccoth, arccsc, arccsch, arcsec, arcsech, arcsin, arcsinh, arctan, arctanh, cos, cosh, cot, coth, csc, csch, dilog, erf, erfc, exp, ln, sec, sech, sin, sinh, tan, tanh

__a__ := 2 &+- 0.1;

__b__ := 3 &+- 0.05;

__s__ := __a__ + __b__;

__p__ := __a__ * __b__;

__sine__ := sin(__a__);