Time Conversions using the HP33S calculator

Values for time (in hours, H), or angles (in degrees, D) can be converted between a decimal form (H.h or D.d) and a minutes-seconds form (H.MMSSss or D.MMSSss) using the LS, then HR or RS, then HMS keys

To convert between decimal fractions and minutes-seconds:
Key in the time or angle (in decimal form or minutes-seconds form) that will be converted.
Press RS, then HMS or LS, then HR. The result is displayed.
Example of converting time formats 
How many minutes and seconds are there in 1/7 of an hour? Use FIX 6 display format.

Press LS, DISP, FX, then 6 - Sets FIX 6 display format
 
Press [.], 1, [.]. then 7  0 1/7_   1/7 as a decimal fraction
 
Press RS, then HMS  0.083429  Equals 8 minutes and 34.29 seconds
 
Press LS, DISP, FX, then 4  0.0834  Restores FIX 4 display format 
 
Angle conversions 

When converting to radians, the number in the X-register is assumed to be degrees; when converting to degrees, the number in the X-register is assumed to be radians.

To convert an angle between degrees and radians

Key in the angle (in decimal degrees or radians) that will be converted.
Press RS, then RAD or LS, then DEG. The result will be displayed.