I have used a HP-6S for several years as my "shirt pocket" calculator. Long enough to have replaced the original battery with no problem. But today, it froze in the Radians mode with only partial segments showing and no keystrokes would change the frozen condition. Unit would sometimes show multiple decimal points.

Since there is no keystroke method to do a reset, and no reset switch, I removed the battery and shorted the battery terminals for about 30 seconds. When I removed the short, all possible display segments and indicators were on. Pressing Clear then restored normal operation with only the Solar power.

I reinstalled the battery and everything now seems fine.

As a cheap hand held, the HP-6s is superb. Not very good on a desktop as it will "walk" all over the desktop as keys are pressed.

I like the solar version. I have three 6-s solar units. Any complex calculations I want to do I use Excel, Matlab, and so on.

Namir