Calculator UI Design

I started this design by looking for inspirations and common designs ideas from different mobile's calculator app. After that I sketched some ideas and ended up choosing the one that I found to be minimalistic and also chose a dark theme for this because it's good for the eye. Even though it took me quite a while to space and design things out evenly from a 4x5 grid to 5x7 grid from a standard to scientific, in the end it was all worth it.