Pressing C and CE

I do this every day.

If you just want to clear the last number like say you wanted to do 2+13 but you typed 4. Hit C
If you want to clear the whole equation hit CE

C is clear. (the line)
CE is clear everything. (everything)

Confession time: My calculator has a percentage button, making the whole financial unit I just did really really f**king easy. My maths teacher thinks that I'm gifted or something ._.