(a) The formula for pressure, with values plugged in for the Sun's
mass and radius, comes out to

 P = 19 * (GM/R^2) * (M/R^2) = 19 * GM^2/R^4

   = 19 * (6.67 * 10^(-11)) * (2.0 * 10^30 kg)^2 / (7.0 * 10^8 m)^4

   = 2.1 * 10^16 N/m^2

Compared to Earth's atmospheric pressure of 1.01 * 10^5 N/m^2, this is

   (2.1 * 10^16) / (1.01 * 10^5) = 200 billion times greater.


(b) If we treat the Sun as an ideal gas and use P = nkT, then use the
values given for n and k, we get

 (2.1 * 10^16 N/m^2) = (1.0 * 10^32/m^3) * (1.38 * 10^(-23) J/K) * T

 and thus T = (2.1 * 10^16) / (1.38 * 10^9) = 1.5 * 10^7 K

or 15 million degrees Kelvin.  Some hot things on Earth include the Sahara
Desert (about 330 K), a blast furnace (about 2000 K), light bulb filaments
(about 2500 K), and our planet's molten core (about 4000-6000 K).  None of
these are even one-thousandth the temperature at the Sun's core.  However,
human beings are able to produce Sun-like temperatures artificially: the
temperature of a nuclear explosion can reach 10 million degrees K.