To find the number of different outcomes when tossing a penny 4 times, you can use the concept of permutations.
Each time you toss the penny, there are 2 possible outcomes: either it lands on heads or tails. Since there are 4 tosses, you multiply the number of outcomes together:
2 (outcomes for each toss) x 2 x 2 x 2 = 16
Therefore, there are 16 different outcomes when you toss a penny 4 times.