If i flipped a regular coin 1000 times, and happened to get 900 heads in a row, you may think 'hey, something is wrong with this coin' - however, could you be s

If i flipped a regular coin 1000 times, and happened to get 900 heads in a row, you may think 'hey, something is wrong with this coin' - however, could you be sure something is up? How would you go about telling whether something is really up, or if this is just a fluke chance this one time? The motivation for the p-value is to tell you what the probability of a fluke chance this would be. The way to do better is to run the experiment over and over, flipping this coin 1000 times again, and again. However, since science experiments are extremely expensive, instead we only run them one time, and try to 'make sure this wasnt some fluke chance'.