Obviously you have a number of HP calculators on your desk and in the showroom glass cupboard. And obviously you are addicted to the RPN method of calculating. But now and then you are away from your precious toys and stuck with your phone or PC with a much less than optimal “calculator” program.
Here’s a tip: Get yourself a copy of Free42 by Thomas Okken.
It’s the coolest desktop/mobiletop calculator in town.
Just my 2 cents.