Daily UI Day 4: Fibonacci Calculator App

Daily UI Day 4 Design Hint...
Design a calculator. Standard, scientific, or specialty calculator for something such as a mortgage? Is it for a phone, a tablet, a web app?
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This is a calculator used in stocks for prediction purposes, apparently. I had a thing for the fibonacci number and the golden ratio and was curious whether there was a calculator that made use of it -- and wala, the internet says yes. This is perhaps how it could look like on an app!