Probability calculation question (simple):

If I had five cards, (let's say numbered 1~5) what is the probability of one card showing same side for 5 times when the cards are thrown on the floor? We don't care about the cards that showed different side during the 5 times. So, if I had only one card showing same side during 5 times of being thrown on the floor, what is the percentage chance that happening and how do you calculate that? Thank you so much in advance.

Since there are 2 sides to a card, the probability of any card showing up is (1/2)
The probability of the same side coming up 5 times = (1/2)^5 = 1/32
% chance of this happening = (1/32)*100 = 100/32 = 3.125%

let two cards sowing the sides A and B, there are 2^5 = 32 results
let us consider one card shows always the side A
the remaining four cards may show the sides A or B
that is 0A,1A,2A,3A,4A
thus probability of showing one A out of five cards is
(4C0+4C1+4C2+4C3+4C4)/32 = (1+4+6+4+1)/32 = 16/32 = 1/2

If your question is regarding
only one specific card

and you want to have the same
side
chances is (1/2)^5=1/32=3.13 percent

(in this question number of cards
which is 5 is not relevant)