As a follow-up to the idea that the built-in calculator should ignore commas in numbers, if the answer field for numerical questions would allow algebraic operations, there would be no need for ever using the calculator.  This is how Google works and most modern browsers.  If you type any equation into the address bar ending with an equal sign, the browser just calculates the arithmetic of the equation you typed.  For example, if I type this into nearly any browser address bar or any search engine:

2,000+3,000/4=

Upon pressing enter, the browser calculates the result and shows the answer along with a clearer version of the equation syntax: 

2000+(3000÷4)=2750

Not only would that solve the comma problem in KA (as mentioned at the link), but it would also nearly eliminate the need to use up screen real estate for a bulky calculator and it would make calculations easier.  The calculator is fine as an option for beginning students, but it is just more awkward for anyone who can write the equation into the answer field.

When this is done, it would be ideal for KA to show both the equation along with the calculated answer just like browsers and search engines do (as demonstrated above).