Looking to find a Mac Calculator app that will do specific functions with a button is pressed (i.e. 100 x PRESS button which might be x 1.5 = ) Looking to save some time.
What you are looking for is a programmable calculator app with repurposable keys. Hewlett-Packard calculators have emulator apps for Mac; I run HP-15C, HP-48G, HP-67, and HP-41C on my Macs, iPhone, and iPad. The actual calculators offered such capabilities, although not all the above models. On emulators, I haven't tried it, but I guess your best chance might be with the 41C. The specific app is under the name "my41CX" and its interface looks like this:
However, if your goal is to save time, why don't you try to learn the so-called RPN arithmetic with any of these HP apps? With some training, you will be able to save a lot of time. After all, the HP calculators have been famous exactly for their RPN logic. You may find a lot on the Internet; also, the calculators' manuals are legally pdf downloadable from the Hewlett-Packard website.
I use an app called “Retro 15C” that emulates, well, the HP 15C and an app called “RPN 30” that is my main iOS/iPad calculator. On macOS I use Apple’s stock calculator set to RPN mode.
I’ve been running all of these for years without any problems. It’s been awhile since I looked, but my ideal would be a free HP 12C (HP’s classic financial calculator) emulator.
RPN is easy to learn and a big timesaver. It is definitely worth the short time required to become proficient (for those who remember, the learning curve is much shorter and gently sloped than with Palm OS).
I've use PCalc for many years; https://www.pcalc.com/. I bought the iPhone version in 2010 and the Mac version in 2014; they're both worth having. It has an RPN mode, which I always use. In the Mac version, you can define custom functions and assign keyboard shortcuts to them.