Let's order the scores to make them easier to look at:
50, 64, 77, 77, 77, 80, 84, 90.
The most frequently occurring number in this list is 77, so 77 is the mode of the test scores. Getting a 77 must have been fashionable that day (although at Shmoop we think getting 100 is more fashionable, but that's just us).
The high temperatures in a very cold town in Canada over one week were
-20, 0, -5, 0, 0, 1, 0.
What is the mode of the temperatures?
Since 0 occurs more than any other number in the list, 0 is the mode. Boy, we bet people were sweatin' on that 1-degree day.
It's possible for a list of values to have multiple modes, or no modes at all.