The gases law is PV = nRT, you solve for n = number of moles:

n=PV/RT where \(\displaystyle{P}={1.01}\times{10}^{{-{13}}}{P}{a},{V}={1}\times{10}^{{-{6}}}{m}^{{{3}}}\), R = 8.31 and T = 293 K, then remember that 1 molehas \(\displaystyle{6.022}\times{10}^{{{23}}}\) molecules

n=PV/RT where \(\displaystyle{P}={1.01}\times{10}^{{-{13}}}{P}{a},{V}={1}\times{10}^{{-{6}}}{m}^{{{3}}}\), R = 8.31 and T = 293 K, then remember that 1 molehas \(\displaystyle{6.022}\times{10}^{{{23}}}\) molecules