1.8 x 10^23 calcium ions
Each mole of CaCl2 will produce 1 mole of calcium ions. So just multiply the number of moles of CaCl2 by avogadro's number. Therefore
0.3 * 6.0221409 x 10^23 = 1.806642 x 10^23
So there will be 1.8 x 10^23 calcium ions in 0.3 moles of CaCl2.