Find all integers n such that when the clock strikes n o'clock, the acute angle between the hour and minute hands is 90 degrees. Enter your answer as a comma-separated list.

Guest May 21, 2021

#1**0 **

*Find all integers n such that when the clock strikes n o'clock, the acute angle between the hour and minute hands is 90 degrees.*

When a clock stricks on the hour, the minute hand has to be on the 12.

The only two places the hour hand can be to make a 90^{o} angle are on the **3** or the **9**.

*edited to add....* The above assumes a 12-hour clock. If it's a 24-hour clock, you can figure it out the same way.

Guest May 21, 2021

edited by
Guest
May 21, 2021