Please can someone explain to me why the C of my calculator isn't working?

Question

https://code.sololearn.com/WL7Am0XpuHNE/?ref=app

Answer 1

Look at it again, made some changes

Answer 2

Here are corrected some syntax etc. errors
https://code.sololearn.com/W6MOPjc4W20U/?ref=app

Answer 3

Thanks but the clear still isn't working