I love this calculator but.. Theres a slight lag on entry. I also would like to see an option for the vibration to be switched off. The other major complaint is that attempts at doing any formula with the sum causes the next equation to be thrown off by the first unless you clear and re-enter the beginning number.
Added degrees and gradians.
Added ability to disable vibration.
Added ability to change buttons position.
Excellent scientific calculator with expressions, fractions, repeating decimals.