You haven't provided the specific ionic compound you're asking about. To determine the number of K+ and S2- ions in a formula unit, we need to know the chemical formula of the ionic compound.

Here's how to figure it out:

1. Identify the charges: You've already given the charges: K+ and S2-.

2. Determine the ratio: To achieve electrical neutrality, the charges must balance. This means we need two K+ ions (total charge +2) for every one S2- ion (charge -2).

3. Write the formula: The formula unit would be K2S.

Therefore, there would be two K+ ions and one S2- ion in a formula unit of K2S.

Let me know if you have another ionic compound in mind, and I can help you determine the number of ions in its formula unit!