1. **State the problem:** We want to find the probability of obtaining exactly three heads when tossing 3 coins simultaneously. 2. **Formula and rules:** The probability of an event is given by $$\text{Probability} = \frac{\text{Number of favorable outcomes}}{\text{Total number of possible outcomes}}$$ Each coin has 2 possible outcomes: Head (H) or Tail (T). 3. **Calculate total outcomes:** For 3 coins, total outcomes are $$2^3 = 8$$ These outcomes are: HHH, HHT, HTH, THH, HTT, THT, TTH, TTT. 4. **Count favorable outcomes:** The favorable outcome for exactly three heads is only one: HHH. 5. **Calculate probability:** $$\text{Probability} = \frac{1}{8}$$ 6. **Final answer:** The probability of obtaining three heads when tossing 3 coins simultaneously is $$\boxed{\frac{1}{8}}$$