Handy but
If you click the “=“ button twice it goes to 00:00 so it looks like it’s cleared the memory but actually the previous result is still in memory, and if you add another number it will add to what is hidden in memory, so if you aren’t aware of this you will get the wrong result. Most calculators would just keep adding the most recently entered number if you click “=“ multiple times, so this is unexpected. Just have to remember to always click AC between calculations.