There are 2 outcomes you can get from one toss, heads and tails. Therefore, if you tossed it once, the probability of landing tails would be 1/2, or 50%. Since you toss it 5 times, you will multiply the probability of one toss by five. 1/2x5 = 1/10, so your probability of landing tails on every toss when thrown 5 times is 1/10, or 10% :)
