The first thing to do is rewrite the number of Ni atoms in a form that can make the calculations easier. Use scientific notation to help with that
6,000,000,000 = 6.0 * 10^(9) - six followed by nine zeros.
Next, focus on how many atoms you would get if you had exactly one mole of Ni. As you know, one mole of Ni has 6.022 * 10^(23) atoms of Ni.
If you compared these two numbers, 6.0 * 10^(9) and 6.022 * 10^(23), it'll be obvious that you have less than 1 mole.
6.0 * 10^(9)" atoms of Ni" * ("1 mole of Ni")/(6.022 * 10^(23)"atoms of Ni") ~= 1.0 * 10^(-14)" moles of Ni"
In other words, 1/10^(14)"th" of "1 mole of Ni" contains 6.0 * 10^(9) atoms of Ni.
