The probability of a coin landing heads up at least once equals 1 minus the probability of landing tail up all three times:
probability of a coin landing heads up at least once = 1 - (probability of landing tail up all three times)
So, let's first find the probability of that coin landing tail up all three times.
The probability of landing tail up the first time the coin is flipped is 1/2 because the result can only be tail up or head up (the probability is 1/2 for each result).
Now, the probability of the coin landing tail up is the same for each flippering, since they are independent events.
Then, the probability of it landing tail up three times is given by the product:
1/2 * 1/2 * 1/2 = 1/8
Finally, the probability of a coin landing heads up at least once is:
1 - 1/8 = (8 - 1)/8 = 7/8 = 0.875
Therefore, the answer is 7/8, which is the same as 0.875.