Data sufficiency (Blue book)
Page 103: Problem: 79
The explanation of the answer says 16.5 minutes before 2:50PM, the digital clock may show either 2:33 or 2:34.
I don't think that is true. The digital clocks I have seen always shows full hour, full minute numbers. It's the analog which tend to show half minute (if seen carefully) when seconds are not complete.
In the case it has to show 2:33. And if it has to show seconds as well, then it will show 2:33:30. Unless there is evidence that the microchips for clocks come with different algorithm depending on whether to show seconds or not.