When 1 is thrown, there are two possibilities, namely 1 positive sum 1 negative.

There are two possibilities when casting No.2, two heads and two tails, which are combined into four possibilities: 1 head, 1 head, 1 tail, 1 tail, 1 tail, and two tails, in no particular order, so the mathematical calculation is p22 = 2 * 2.

And so on, three pieces are P32=2*2*2=8.

Four pieces are P42=2*2*2*2= 16, which is the possible total.

In the positive proof method, as long as there are two coins facing up when throwing, the first time throwing, there are four chances of facing up, the second time there are three chances of facing up, or two tails facing up, then the mathematical formula related to the order is C42=4*3/2=6, and the probability is 6/ 16=37.5%.

To the contrary, there is only one possibility that all four heads are up and only one possibility that all four tails are up.

There are four possibilities: 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 3 This excludes the case of 10, and the remaining six are 2 and 4.

So the probability of 6/ 16 = 3/8 is 37.5%.