2^7 because each time you flip the coin there can be two outcomes (heads or tails) and you have to multiply by 2 each time (2x2x2x2x2x2x2) to account for all the different possibilities for instance you could flip heads, tails, heads, heads, tails, tails, tails or you could flip tails, tails, tails, heads, heads, tails, heads or all heads or all tails which is why it’s 2^7